docs: add commit parser docs

docs/source/commit_parser.rst

@@ -0,0 +1,18 @@
+Commit Message Parser
+======================
+
+Overview
+--------
+The commit message parser is designed to extract and organize commit message components into a structured format. It identifies the summary, body, and footer from commit messages that follow common conventions.
+
+Features
+--------
+The commit parser offers several key features. First, it performs summary extraction by capturing the first line of the commit message and designating it as the summary.
+
+Next, it includes body extraction, which collects all lines that follow the summary while excluding any footer lines.
+
+In addition, the parser recognizes and collects footer lines, accommodating special tags such as “BREAKING CHANGE” as well as any user-defined footer labels.
+
+Moreover, the parser effectively handles whitespace, preserving leading and trailing whitespace and newlines to maintain the original formatting of the commit message.
+
+Finally, it incorporates error handling by raising a ValueError when an empty commit message is provided, thus preventing potential processing errors.

docs/source/index.rst

@@ -16,4 +16,5 @@ Lint git commits in a Conventional Commits manner in pure Python.
    get_started
    cli
    user_config
-   rules_config
+   rules_config
+   commit_parser