docs: update readme for partify with setup-terraform

Signed-off-by: Dmitry Kisler <admin@dkisler.com>

README.md

@@ -21,6 +21,222 @@ steps:
 - uses: opentofu/setup-opentofu
 ```
 
+A specific version of OpenTofu CLI can be installed:
+
+```yaml
+steps:
+- uses: opentofu/setup-opentofu
+  with:
+    tofu_version: 1.6.0-alpha1
+```
+
+Credentials for Terraform Cloud ([app.terraform.io](https://app.terraform.io/)) can be configured:
+
+```yaml
+steps:
+- uses: opentofu/setup-opentofu
+  with:
+    cli_config_credentials_token: ${{ secrets.TF_API_TOKEN }}
+```
+
+Credentials for Terraform Enterprise (TFE) can be configured:
+
+```yaml
+steps:
+- uses: opentofu/setup-opentofu
+  with:
+    cli_config_credentials_hostname: 'tofu.example.com'
+    cli_config_credentials_token: ${{ secrets.TF_API_TOKEN }}
+```
+
+The wrapper script installation can be skipped by setting the `tofu_wrapper` variable to `false`:
+
+```yaml
+steps:
+- uses: opentofu/setup-opentofu
+  with:
+    tofu_wrapper: false
+```
+
+Subsequent steps can access outputs when the wrapper script is installed:
+
+```yaml
+steps:
+- uses: opentofu/setup-opentofu
+
+- run: tofu init
+
+- id: plan
+  run: tofu plan -no-color
+
+- run: echo ${{ steps.plan.outputs.stdout }}
+- run: echo ${{ steps.plan.outputs.stderr }}
+- run: echo ${{ steps.plan.outputs.exitcode }}
+```
+
+Outputs can be used in subsequent steps to comment on the pull request:
+
+> **Notice:** There's a limit to the number of characters inside a GitHub comment (65535).
+>
+> Due to that limitation, you might end up with a failed workflow run even if the plan succeeded.
+>
+> Another approach is to append your plan into the $GITHUB_STEP_SUMMARY environment variable which supports markdown.
+
+```yaml
+defaults:
+  run:
+    working-directory: ${{ env.tf_actions_working_dir }}
+permissions:
+  pull-requests: write
+steps:
+- uses: actions/checkout@v3
+- uses: opentofu/setup-opentofu
+
+- name: OpenTofu fmt
+  id: fmt
+  run: tofu fmt -check
+  continue-on-error: true
+
+- name: OpenTofu Init
+  id: init
+  run: tofu init
+
+- name: OpenTofu Validate
+  id: validate
+  run: tofu validate -no-color
+
+- name: OpenTofu Plan
+  id: plan
+  run: tofu plan -no-color
+  continue-on-error: true
+
+- uses: actions/github-script@v6
+  if: github.event_name == 'pull_request'
+  env:
+    PLAN: "tofu\n${{ steps.plan.outputs.stdout }}"
+  with:
+    github-token: ${{ secrets.GITHUB_TOKEN }}
+    script: |
+      const output = `#### OpenTofu Format and Style 🖌\`${{ steps.fmt.outcome }}\`
+      #### OpenTofu Initialization ⚙️\`${{ steps.init.outcome }}\`
+      #### OpenTofu Validation 🤖\`${{ steps.validate.outcome }}\`
+      <details><summary>Validation Output</summary>
+
+      \`\`\`\n
+      ${{ steps.validate.outputs.stdout }}
+      \`\`\`
+
+      </details>
+
+      #### OpenTofu Plan 📖\`${{ steps.plan.outcome }}\`
+
+      <details><summary>Show Plan</summary>
+
+      \`\`\`\n
+      ${process.env.PLAN}
+      \`\`\`
+
+      </details>
+
+      *Pusher: @${{ github.actor }}, Action: \`${{ github.event_name }}\`, Working Directory: \`${{ env.tf_actions_working_dir }}\`, Workflow: \`${{ github.workflow }}\`*`;
+
+      github.rest.issues.createComment({
+        issue_number: context.issue.number,
+        owner: context.repo.owner,
+        repo: context.repo.repo,
+        body: output
+      })
+```
+
+Instead of creating a new comment each time, you can also update an existing one:
+
+```yaml
+defaults:
+  run:
+    working-directory: ${{ env.tf_actions_working_dir }}
+permissions:
+  pull-requests: write
+steps:
+- uses: actions/checkout@v3
+- uses: opentofu/setup-opentofu
+
+- name: OpenTofu fmt
+  id: fmt
+  run: tofu fmt -check
+  continue-on-error: true
+
+- name: OpenTofu Init
+  id: init
+  run: tofu init
+
+- name: OpenTofu Validate
+  id: validate
+  run: tofu validate -no-color
+
+- name: OpenTofu Plan
+  id: plan
+  run: tofu plan -no-color
+  continue-on-error: true
+
+- uses: actions/github-script@v6
+  if: github.event_name == 'pull_request'
+  env:
+    PLAN: "tofu\n${{ steps.plan.outputs.stdout }}"
+  with:
+    github-token: ${{ secrets.GITHUB_TOKEN }}
+    script: |
+      // 1. Retrieve existing bot comments for the PR
+      const { data: comments } = await github.rest.issues.listComments({
+        owner: context.repo.owner,
+        repo: context.repo.repo,
+        issue_number: context.issue.number,
+      })
+      const botComment = comments.find(comment => {
+        return comment.user.type === 'Bot' && comment.body.includes('OpenTofu Format and Style')
+      })
+
+      // 2. Prepare format of the comment
+      const output = `#### OpenTofu Format and Style 🖌\`${{ steps.fmt.outcome }}\`
+      #### OpenTofu Initialization ⚙️\`${{ steps.init.outcome }}\`
+      #### OpenTofu Validation 🤖\`${{ steps.validate.outcome }}\`
+      <details><summary>Validation Output</summary>
+
+      \`\`\`\n
+      ${{ steps.validate.outputs.stdout }}
+      \`\`\`
+
+      </details>
+
+      #### OpenTofu Plan 📖\`${{ steps.plan.outcome }}\`
+
+      <details><summary>Show Plan</summary>
+
+      \`\`\`\n
+      ${process.env.PLAN}
+      \`\`\`
+
+      </details>
+
+      *Pusher: @${{ github.actor }}, Action: \`${{ github.event_name }}\`, Working Directory: \`${{ env.tf_actions_working_dir }}\`, Workflow: \`${{ github.workflow }}\`*`;
+
+      // 3. If we have a comment, update it, otherwise create a new one
+      if (botComment) {
+        github.rest.issues.updateComment({
+          owner: context.repo.owner,
+          repo: context.repo.repo,
+          comment_id: botComment.id,
+          body: output
+        })
+      } else {
+        github.rest.issues.createComment({
+          issue_number: context.issue.number,
+          owner: context.repo.owner,
+          repo: context.repo.repo,
+          body: output
+        })
+      }
+```
+
 ## Inputs
 
 The action supports the following inputs:
@@ -29,7 +245,11 @@ The action supports the following inputs:
   place within the credentials block of the OpenTofu CLI configuration file. Defaults to `app.terraform.io`.
 - `cli_config_credentials_token` - (optional) The API token for a Terraform Cloud/Enterprise instance to
   place within the credentials block of the OpenTofu CLI configuration file.
-- `tofu_version` - (optional) The version of OpenTofu CLI to install. If no version is given, it will default to `latest`.
+- `tofu_version` - (optional) The version of OpenTofu CLI to install. Instead of a full version string,
+  you can also specify a constraint string (see [Semver Ranges](https://www.npmjs.com/package/semver#ranges)
+  for available range specifications). Examples are: `<1.6.0-beta`, `~1.6.0-alpha`, `1.6.0-alpha2` (all three installing
+  the latest available `1.6.0-alpha2` version). Prerelease versions can be specified and a range will stay within the
+  given tag such as `beta` or `rc`. If no version is given, it will default to `latest`.
 - `tofu_wrapper` - (optional) Whether to install a wrapper to wrap subsequent calls of
   the `tofu` binary and expose its STDOUT, STDERR, and exit code as outputs
   named `stdout`, `stderr`, and `exitcode` respectively. Defaults to `true`.