Reconcile render docs

Author: lcawl

docs/cli/changelog/cmd-render.md

@@ -25,6 +25,33 @@ The default output (`--file-type markdown`) generates multiple files:
 
 `--file-type asciidoc` generates a single file with all sections in order: security updates, bug fixes, highlights, new features and enhancements, breaking changes, deprecations, known issues, documentation, regressions, and other changes. The asciidoc output uses attribute references for links (for example, `{repo-pull}NUMBER[#NUMBER]`).
 
+### GFM format
+
+When `--file-type gfm` is specified, the command generates a single GitHub Flavored Markdown file optimized for GitHub releases:
+
+- `changelog.md` - Contains all sections in a single file with clean headings
+- Clean section headings without anchor links (for example, `### Features and enhancements`)
+- Simplified structure focused on readability
+- Suitable for copy/pasting into GitHub releases
+
+The GFM output includes the following sections in order when entries are present:
+
+- Highlights (only included when at least one entry has `highlight: true`)
+- Features and enhancements
+- Breaking changes
+- Deprecations
+- Bug fixes (includes security updates)
+- Known issues
+- Documentation
+- Regressions
+- Other changes
+
+AsciiDoc output ignores the `--dropdowns` flag and always uses a standardized format with the following characteristics:
+
+- Multi-block entries (containing description, Impact, and Action sections) use proper list continuation markers (`+`) to maintain list structure
+- Strong text formatting uses idiomatic single asterisk syntax (`*Impact:*`, `*Action:*`) following AsciiDoc best practices
+- All content blocks are properly attached to their parent list items for correct rendering
+
 ### Multiple PR and issue links
 
 Changelog entries can reference multiple pull requests and issues via the `prs` and `issues` array fields. All links are rendered inline:
@@ -36,10 +63,11 @@ Changelog entries can reference multiple pull requests and issues via the `prs`
 ## Examples
 
 ```sh
-# Render a single bundle
+# Render a single bundle with subsections
 docs-builder changelog render \
   --input "./docs/changelog/bundles/9.3.0.yaml" \
-  --output ./release-notes
+  --output ./release-notes \
+  --subsections
 
 # Render with explicit changelog dir and repo
 docs-builder changelog render \
@@ -55,4 +83,16 @@ docs-builder changelog render \
 docs-builder changelog render \
   --input "./public-bundle.yaml|./changelog|elasticsearch|keep-links,./private-bundle.yaml|./private-changelog|internal-repo|hide-links" \
   --output ./release-notes
+
+# Render with dropdown format
+docs-builder changelog render \
+  --input "./bundles/9.3.0.yaml|./changelog|elasticsearch" \
+  --output ./release-notes \
+  --dropdowns
+
+# Render as GitHub Flavored Markdown
+docs-builder changelog render \
+  --input "./bundles/9.3.0.yaml|./changelog|elasticsearch" \
+  --output ./github-release \
+  --file-type gfm
 ```