docs(Composition|Shorthand): improve pages

[layershifter]

This PR:

• renames Augmentation page to Composition because previous name it's not clear
• adds a section about unhandled props to Composition page
• updates comments on Shorthand Props page

[codecov-io]

Codecov Report

Merging #3707 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3707   +/-   ##
=======================================
  Coverage   99.83%   99.83%           
=======================================
  Files         175      175           
  Lines        3120     3120           
=======================================
  Hits         3115     3115           
  Misses          5        5

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