Improve protocols index page

Review Request #820 — Created July 18, 2021 and submitted — Latest diff uploaded

Information

pidgin/nest
default
85ef613c0c2c

Reviewers

Make the protocols index page more detailed:

- Explain what are services/protocols.
- Make it clear that we will only answer questions for protocols that come
  built into Pidgin.
- Explain that for third party protocol plugins users need to ask questions
  directly to their respective authors.

Ran dev-server.sh and verified contents look as intended.