Fix args for stricter Google docstring parsing by Griffe

[hugovk]

Re: mkdocstrings/griffe@6a8a228 and mkdocstrings/griffe#204

Griffe 0.35.2 has stricter parsing of Google docstrings, and needs a newline before the args: section.

After 0.35.2 without the fix:

Before 0.35.2, and after with this PR:

---

Also fix some warnings:

INFO    -  Doc file 'index.md' contains an unrecognized relative link 'number', it was left as is. Did you mean 'number.md'?
INFO    -  Doc file 'index.md' contains an unrecognized relative link 'time', it was left as is. Did you mean 'time.md'?
INFO    -  Doc file 'index.md' contains an unrecognized relative link 'filesize', it was left as is. Did you mean 'filesize.md'?
INFO    -  Doc file 'index.md' contains an unrecognized relative link 'i18n', it was left as is. Did you mean 'i18n.md'?

---

Also fix a deprecation warning:

Before:

❯ mkdocs serve
INFO    -  Building documentation...
INFO    -  mkdocstrings: DEPRECATION: mkdocstrings' watch feature is deprecated in favor of MkDocs' watch feature, see https://www.mkdocs.org/user-guide/configuration/#watch
INFO    -  Cleaning site directory
INFO    -  Documentation built in 0.39 seconds
INFO    -  [13:11:27] Watching paths for changes: 'docs', 'mkdocs.yml', 'src/humanize', 'README.md'
INFO    -  [13:11:27] Serving on http://127.0.0.1:8000/

After:

❯ mkdocs serve
INFO    -  Building documentation...
INFO    -  Cleaning site directory
INFO    -  Documentation built in 0.42 seconds
INFO    -  [13:26:23] Watching paths for changes: 'docs', 'mkdocs.yml', 'README.md', 'src/humanize'
INFO    -  [13:26:23] Serving on http://127.0.0.1:8000/

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (9a67390) 99.19% compared to head (d2d0110) 99.19%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #146   +/-   ##
=======================================
  Coverage   99.19%   99.19%           
=======================================
  Files           9        9           
  Lines         746      746           
=======================================
  Hits          740      740           
  Misses          6        6           

Flag	Coverage Δ
macos-latest	97.58% <ø> (ø)
ubuntu-latest	97.58% <ø> (ø)
windows-latest	96.11% <ø> (ø)

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Files	Coverage Δ
src/humanize/filesize.py	100.00% <ø> (ø)
src/humanize/number.py	96.98% <ø> (ø)

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