Use make automatic variables to install updated manuals

Make will choose modified manual from build directory or original from source
directory automagically. Take advantage of install tool feature.
Install all files in single command instead of iterating on each of them.

(cherry picked from commit 88f913ac)
13 jobs for modified-manual-install-oot-v9_11 in 7 minutes and 19 seconds (queued for 7 seconds)