PDB-127 Remove references to reports being 'experimental'

Reports haven't been really experimental for some time - so this patch removes
any reference to 'experimental' from the formal documentation.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #808 from kbarber/ticket/1.5.x/PDB-127-remove_experimental_status_for_reports

PDB-127 Remove references to reports being 'experimental'