pidgin/pidgin

Add doc alias target when possible.

2020-11-14, Elliott Sales de Andrade
f88830d41330
Add doc alias target when possible.

Testing Done:
Build with `ninja -C build doc` and see all docs being built.

Reviewed at https://reviews.imfreedom.org/r/216/
syntax: glob
.*.swp
.DS_Store
.flatpak-builder
*.pyc
*~
\#*\#
subprojects/*/
syntax: regexp
^build(.+)?\/
win32-install-dir(\.release)?