docs: refine docs generation script and template

[huxuan]

• I have added a news fragment under changelog.d/ (if the patch affects the end users)

Summary of changes

Fix #1325

1. Add missing command line help, install-all, uninject, reinstall, interpreter, ensurepath, environment, completions.
2. Order the params the same with pipx --help.
3. Order the docs template the same with pipx --help.
4. Remove redundant version in params.
5. Remove {" ".join(args[2:])} which leads to redundant --help in docs.

Test plan

Docs generated from pull request: https://pipx--1328.org.readthedocs.build/1328/docs/

Tested by running

# command(s) to exercise these changes
nox -s build_docs
# or
nox -s watch_docs

[chrysle]

Looks good, thank you!