chore(how-to-contribute): remove portion about (re)moving declarations

[grunweg]

from the PR description. This clogs up the template and has not been used in practice at all. In the future, semantic diffing will provide this information.

[grunweg]

Needs discussion about reviewers first: there was support in-person at the MI retreat.

[faenuccio]

Needs discussion about reviewers first: there was support in-person at the MI retreat.

What do you mean? That this PR is actually on hold?

[grunweg]

Perhaps I meant "I want to ask more reviewers for their opinion". What do you think? This changes written policy, although one we hardly ever followed.

[b-mehta]

I'm not sure about this, I find the "moves" section helpful to read and particularly helpful in the changelog.

[grunweg]

As discussed in person: a solution satisfying both needs could be to have a Lean-aware declarations diff (and then remove this portion of the PR message as it would be redundant). @adomani worked on Lean-aware declarations diff and thinks it's doable --- I think it would be great to have!

[faenuccio]

Perhaps I meant "I want to ask more reviewers for their opinion". What do you think? This changes written policy, although one we hardly ever followed.

I realise I don't have a strong opinion and I'm happy to delegate the group of people who seem to be actively discussing this.