Conform to doc requirements so that the docs look more beautiful

[alexjbest]

These are mostly either of the form of unindenting text that was accidentally put in a code block, or correctly adding :: or EXAMPLES:: so that docs render nicely.

📚 Description

📝 Checklist

• I have made sure that the title is self-explanatory and the description concisely explains the PR.
• I have linked an issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation accordingly.

⌛ Dependencies

[tscrim]

All are just a minor formatting issue of .:: displaying at .: in the doc. Either change to . :: (for . output) or :: (for : output).

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: +0.01 🎉

Comparison is base (52a81cb) 88.57% compared to head (971c0b1) 88.59%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #35069      +/-   ##
===========================================
+ Coverage    88.57%   88.59%   +0.01%     
===========================================
  Files         2140     2140              
  Lines       397273   397273              
===========================================
+ Hits        351891   351945      +54     
+ Misses       45382    45328      -54     

Impacted Files	Coverage Δ
src/sage/algebras/free_algebra_quotient.py	98.63% <ø> (ø)
src/sage/algebras/iwahori_hecke_algebra.py	82.69% <ø> (ø)
src/sage/algebras/quatalg/quaternion_algebra.py	92.68% <ø> (ø)
src/sage/categories/cartesian_product.py	97.77% <ø> (ø)
src/sage/categories/domains.py	100.00% <ø> (ø)
src/sage/categories/examples/sets_cat.py	100.00% <ø> (ø)
src/sage/categories/magmas.py	97.63% <ø> (ø)
src/sage/coding/abstract_code.py	94.20% <ø> (ø)
src/sage/coding/guruswami_sudan/interpolation.py	100.00% <ø> (ø)
src/sage/coding/linear_code_no_metric.py	96.65% <ø> (ø)
... and 98 more

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[github-actions]

Documentation preview for this PR is ready! 🎉
Built with commit: 971c0b1

[fchapoton]

looks good, thanks