update missing documentation for the last 4 versions
Merge pull request #373 from prashn64/gh-pages

update missing documentation for the 2.2.X
update benchmarks remove unnecessary stuff and update gh-pages docs
update gh-pages coverage output from latest in istanbul
benchmark is using the latest version not 1.2.3
grammar change
Merge pull request #377 from jimmyhchan/gh-pages

Update gh-pages: benchmark, docs, code coverage report