Moved to doc/manuals/, with full commit history, in preceding merge commit.
Now incorporate in the build system.
Build with:
$ autoreconf -fi
$ ./configure --enable-manuals
$ make
Shared files from osmo-gsm-manuals.git are found automatically if
- the repository is checked out in ../osmo-gsm-manuals; or
- if it osmo-gsm-manuals was installed with "make install"; or
- OSMO_GSM_MANUALS_DIR is set.
Related: OS#3385
Change-Id: I7270652de393a98748c0cdc51e626c17ab8f44c2