Improve changelog bundle option descriptions

[lcawl]

This PR improves the command help and the generated CLI docs for the docs-builder changelog bundle command.

In particular, the goal is to make it clearer when there are configuration settings that equate to the command options (particularly since most of the options aren't supported in profile-based commands).

Output

The new output for docs-builder changelog bundle -h includes the same details, for example:

Usage: docs-builder changelog bundle [<profile>] [<profile-arg>] [<profile-report>] [options]

   Aggregate changelog entries matching a filter into a single bundle YAML.
...
Options:
  --all                        Include all changelogs in the directory. This option is not supported in profile-based commands. The equivalent configuration option is bundle.profiles.<name>.products: "* * *".
...
  --directory <dir>            Directory containing changelog YAML files. Uses config bundle.directory or defaults to current directory. This option is not supported in profile-based commands. The equivalent configuration option is bundle.directory. [default: null] [no symlinks] [expand ~ profile]
  --description <string>       Bundle description text with placeholder support ({version}, {lifecycle}, {owner}, {repo}). Overrides bundle.description from config. In option-based mode, placeholders require --output-products. This option is not supported in profile-based commands. The equivalent configuration options are bundle.description or bundle.profiles.<name>.description. [default: null]
...

Generative AI disclosure

1. Did you use a generative AI (GenAI) tool to assist in creating this contribution?

• Yes
• No

2. If you answered "Yes" to the previous question, please specify the tool(s) and model(s) used (e.g., Google Gemini, OpenAI ChatGPT-4, etc.).

Tool(s) and model(s) used: composer-2.5-fast