80668: Lint report doesn't explain how to suppress warnings from Gradle.

Updates the suppress topic emitted at the end of the HTML reports
to include information about suppressing warnings when using Gradle.

While there, I also changed the text format from text to markup such
that the HTML report can (for example) distinguish between text and
identifiers, and the markup format now properly converts non-breaking
spaces into   entities in HTML (which the help topic now uses
to ensure that the XML and build.gradle samples are indented properly).

Finally, I got rid of the <nobr> tags around links; it doesn't seem
to be necessary (and is flagged by http://validator.w3.org.)

Change-Id: I9354ca388739cc016f9bf2b1083cc6251523233c
5 files changed