This adds content to the three stub files.
Corrects the Makefile for incorrect importing of Javascript docs into the Haskell folder.
Corrects community Slack URLs to point to slack.min.io.
This commit also generally cleans up the Installation docs and uses /includes/<platform>/steps-*.rst as a pattern for storing platform-specific tutorials within a single root URL.
Finally, due to API rate limits, this commit adds some Makefile magic to allow skipping of sync'ing dependencies. Pass `make BUILD_DEPENDENCIES=FALSE <platform>` to skip building any deps and use what is already in the branch.
