docs: fix typo

[zizi4n5]

The following typo has been corrected.

1. Corrected instance of "Github readme stats" to "GitHub Readme Stats"
2. Corrected many instances of "Github" to "GitHub"
3. Corrected the default value of an number type was a string type. (e.g. '1800')
4. Unified to 'default', because "default" and 'default' were mixed up.

Thanks for the useful service.
My README is now cool too.

<3

[codecov]

Codecov Report

Merging #245 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #245   +/-   ##
=======================================
  Coverage   95.18%   95.18%           
=======================================
  Files          15       15           
  Lines         415      415           
  Branches      122      122           
=======================================
  Hits          395      395           
  Misses         16       16           
  Partials        4        4           

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[anuraghazra]

@zizi4n5 Thanks for the PR :D