update contributing.rst and docstyle.rst: refer to a bug via bug #1234 + other guidelines

[timotheecour]

principle: "instead of each one guessing or following surrounding code (which encourages dialects), encourage following a single convention"

I don't mind changing that convention to something else that's reasonable, eg bug #1234 but I'd prefer to have a single fixed convention. Doesn't mean past code needs to be changed/edited but at least future code should.

it makes it easier for tooling, as well as simple grep search

refs: https://github.com/nim-lang/Nim/pull/14795/files#r445261335 which was using many different conventions in the same PR:

block: # 9313
block t9458:
# t12398
#7174

=> instead use:
block: # issue #9313

which makes it awkward to search given that 9313 can come from anywhere (eg port number etc)

note

as a side benefit, this will make those issue links clickable, with some browser extensions (eg: https://github.com/sindresorhus/refined-github) as you can see in the updated #14795; (at least when that extension works, refs refined-github/refined-github#3285)

[Araq]

Good, but change it to "bug #123", it's shorter and I think I use it more often.

[Clyybber]

This doesn't belong into NEP1 IMO, but in tests/readme.md.

[alaviss]

Should we be really modifying NEP-1 or should we just write a new one called NEP-2? We can probably use a similar process to IETF RFC: RFCs are immutable and updates are published in the form of a new RFC.

What is the actual process for introducing these NEPs anyway? I think we kinda obsoleted this with RFCs, but I can be wrong.

[Araq]

Er, indeed this belongs to the contributings.rst document!

[timotheecour]

Should we be really modifying NEP-1 or should we just write a new one called NEP-2?

IIUC NEP is obsoleted by RFC's repo, but nep1 became synonymous of style guide; that being said, I wouldn't mind someone (carefully) merging nep1.rst into docstyle.rst or similar, and updating any reference to nep1

Er, indeed this belongs to the contributings.rst document!

indeed.

PTAL (better debate here than in individual PR's about those guidelines)