highlight little known feature

sadly clean up nitrous.io

update award list

Thanks to community members @jelhouss and Angry Cactus   RocketChat/Rocket.Chat#1921

Nitrous.io has been discontinued hence removing from README

word changed for emphasis

* Update deployment section to include snaps

* Update README.md

* Fix Doc path for snaps

added link and corrected stale blackduck link

-  added official app explorer link + logo
-  fixed link from ToC
-  fixed XMPP bridge link

Add blackduck article link

Closes https://github.com/RocketChat/Rocket.Chat/issues/3262

replace `s/wiki/docs`

Changed github wiki links to rocket.chat/docs links since the wiki no longer exists

Support Windows server.    Thanks to community contributor @matholum !!