This does a few things to the home page and all-in-one single
machine install guide:
* Uses code blocks for formatting
* Adds the customary "$" to the console blocks in the
all-in-one single machine install guide
* Instructs to use "sudo su stack" and adds a note about
"sudo visudo" in the all-in-one single machine doc
* Creates a symbolic link to the sample local.conf and links to
it from the install guide (note that local.conf might be old
by now)
* Fixes the .gitignore file to only ignore local.conf in the root
of the repository, otherwise it would ignore local.conf everywhere
including the samples and doc/source/assets directories.
Change-Id: I50ae7bd32c4c1caa2ac8551fc54b31dd2dfae568
584979ce2e