Add a man page for markdown2tex

[Witiko]

In version 3.10.0, we aliased markdown-cli.lua as markdown2tex.lua, which has been made available as the executable markdown2tex in TeX Live 2024, as discussed on [email protected]. Following this exchange, @kberry requested that a man page be added for the script:

Imported the new version and did that for tonight's TL update.

No problem there, but can you also please write or generate a man page for the next release? The distros will appreciate it. afm2tfm.1 is a simple handwritten man page that can serve as a template if needed.

Tasks

• Generate a man page markdown2tex.1 from markdown.dtx and markdown.ins.
• Install the man page in Makefile.

[Witiko]

We should also use this opportunity to flatten the output of markdown2tex for greater ease of use. Specifically, unless the option finalizeCache has been enabled, markdown2tex should produce the top-level TeX output directly, not \input CACHE_FILENAME. Now, if eagerCache has been enabled, the file CACHE_FILENAME may still be produced to speed up future conversions of the same document. However, the file should still be inlined in the output of the command.