Add documentation for how spec files are required/run.

Closes 623.

Signed-off-by: Sam Phippen <samphippen@googlemail.com>
Update the docs for spec/support to include pattern explicitly.

Also adds a changelog entry.

Signed-off-by: Sam Phippen <samphippen@googlemail.com>
Merge pull request #754 from samphippen/document-support

Add documentation for how spec files are required/run.