pidgin/pidgin

Replace mentions of Freenode with Libera and move README.hg to HACKING which just directed to the website
release-2.x.y
2021-06-21, Gary Kramlich
c8d074d77a1e
Replace mentions of Freenode with Libera and move README.hg to HACKING which just directed to the website

Testing Done:
Compiled

Reviewed at https://reviews.imfreedom.org/r/768/
FROM pidgin/release-builder:release-2.x.y AS build
COPY . /pidgin
RUN set -ex && \
cd /pidgin && \
./autogen.sh --enable-debug && \
make -s -j$(nproc) docs
FROM rwgrim/goserve
EXPOSE 3000
COPY --from=build /pidgin/doc/html html