Clean-up and replace Communication chapter

[egpbos]

• Add a section to Best Practices.
  • NLeSC-internal note: refer to the PMP, section "output management"
• Remove the chapter PR
• Afterwards: check for broken links (globally! the PR link checker only checks changed files...)

[egpbos]

Because of the NLeSC-internal reference, this should wait until #394 is merged.

[egpbos]

#394 is merged, this issue is unblocked.

[egpbos]

I'm not sure whether this should go in the software best practices chapter. The communication chapter used to contain points like:

• have a home page
• have a discussion list
• make a demo docker image
• make an online demo (where applicable)
• do a screencast (e.g. on youtube)

While these are all great tips, I feel like this is more about community building. What do others think?

In view of time, I suggest we leave it out for the v1.0 release.