pidgin/pidgin

Remove a reference to a doc file that was in a draft review request

Testing Done:
Ran `ninja pidgin-doc`

Reviewed at https://reviews.imfreedom.org/r/643/
syntax: glob
.*.swp
.DS_Store
.flatpak-builder
*.pyc
*~
\#*\#
subprojects/*/
syntax: regexp
^build(.+)?\/
win32-install-dir(\.release)?
po\/pidgin\.pot$