Move documentation source/ directory to docs/source/

This commit consolidates Sphinx docs resources (specifically source
code) into its own subdirectory to separate documentation code and
feature code. This commit also updates image and code refs to match
new file locations.
Update Sphinx Makefile and make.bat to reflect new documentation resource location

Prior to this commit, Sphinx docs Makefile and make.bat did not point
to the new location of the Sphinx source code resources. This commit
updates makefile references to point to the correct location in the
project file structure.
Add labels to code examples and minor grammar edits

Prior to this commit, readers could not determine where included code
samples came from. This commit adds labels to code segments and makes
a few minor grammar edits.
Merge pull request #4 from osu-cass/maint-3803-edits

Maint 3803 edits