made necessary changes to docs for 2.1 release
Merge pull request #719 from nraychaudhuri/update_documentation_for_2.1

made necessary changes to docs for 2.1 release
Documented thread pools and execution contexts
Update documentation/manual/detailledTopics/configuration/ThreadPools.md

A small typo as mentioned in #721
Modified steps for creating new application
fixed typo
Merge pull request #723 from nraychaudhuri/21_create_new_app

Modified steps for creating new application
Merge pull request #722 from ndeverge/patch-4

Update documentation/manual/detailledTopics/configuration/ThreadPools.md