Add periods for the documentation

[shirayu]

What does this PR do?

Improve document formatting.

Before submitting

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[codecov]

Codecov Report

Merging #8252 (7656520) into master (365a9ba) will decrease coverage by 0%.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #8252   +/-   ##
======================================
- Coverage      88%     88%   -0%     
======================================
  Files         212     212           
  Lines       13701   13701           
======================================
- Hits        12125   12058   -67     
- Misses       1576    1643   +67