[doc] fix pattern for extlinks, use Sphinx-bundled (up2date) napoleon

[marscher]

Changes

• Title elements in ext_links require a template %s. The recently released Sphinx version triggered a warning about it.
• Napoleon used to be loaded as sphinxcontrib.napoleon; However sphinx.ext.napoleon is more recent.

Checks

• updated doc/

[codecov]

Codecov Report

Merging #766 (0fd4190) into master (b859a54) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #766   +/-   ##
=======================================
  Coverage   96.83%   96.83%           
=======================================
  Files          88       88           
  Lines        6009     6009           
=======================================
  Hits         5819     5819           
  Misses        190      190           

Impacted Files	Coverage Δ
weldx/asdf/file.py	96.20% <ø> (ø)

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[github-actions]

Unit Test Results

       1 files  ±0         1 suites  ±0   2m 41s ⏱️ +2s
2 152 tests ±0  2 152 ✔️ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit 0fd4190. ± Comparison against base commit b859a54.

♻️ This comment has been updated with latest results.

[vhirtham]

Thanks for fixing this 👍