docs: add README.md

Author: Robitx

README.md

@@ -1,2 +1,25 @@
-# snippet-permalink-updater-action
-Automates updating Markdown files with permalinks to code snippets
+# Snippet Permalink Updater Action
+
+This GitHub Action automatically updates a Markdown file with a permalink to a specific code snippet.
+
+It's useful for keeping documentation up-to-date with the latest version of your code.
+
+## Features
+
+- Finds a specific snippet in a source file using start and end markers
+- Generates a permalink to the snippet, including the latest commit ID
+- Updates a specified Markdown file with the new permalink
+
+## Usage
+
+To use this action in your workflow, add the following step:
+
+```yaml
+- name: Update Markdown with Snippet Permalink
+  uses: Robitx/snippet-permalink-updater-action@v1
+  with:
+    snippet_file: 'path/to/your/source/file.ext'
+    start_marker: '-- START_MARKER'
+    end_marker: '-- END_MARKER'
+    markdown_file: 'README.md'
+    replace_marker: '-- REPLACE_MARKER'