docs: fix grammar and formatting issues in crun.1.md

[Rajkaran-122]

Description:
This commit fixes a few minor typographical and formatting issues in the crun man page:

• Fixed a missing markdown bold marker for the -u/--user option.
• Fixed grammar: "how the context mount flags works" -> "work".
• Fixed grammar: "each children mount" -> "each child mount".
• Fixed grammar: "an user namespace" -> "a user namespace".

[gemini-code-assist]

Caution

The consumer version of Gemini Code Assist on GitHub has been sunset. All code review activity has officially ceased.

[packit-as-a-service]

Ephemeral COPR build failed. @containers/packit-build please check.

[giuseppe]

thanks,

please fix the commit message with your real name/email.

Also commit the crun.1 file

[giuseppe]

do not use a merge commit, do a proper rebase e.g. git rebase -i origin/main

[giuseppe]

the regenerated crun.1 file is still missing

[Rajkaran-122]

Thanks, sir. I really appreciate your guidance. I'll make sure to follow these practices from now on. This is my first contribution to a large open-source repository, so I'm still learning. Thank you for your feedback.

[giuseppe]

again, you need to rebase, not merge

[Rajkaran-122]

again, you need to rebase, not merge

yes sir i have did it
Please let me know if there's anything else that needs to be updated.

[giuseppe]

LGTM