Instance configuration information does not include max pinned statuses

[nikclayton]

Steps to reproduce the problem

N/A

Expected behaviour

N/A

Actual behaviour

N/A

Detailed description

Per @ClearlyClaire in #25555 (comment), discussing pinned statuses:

5 posts is a hard limit in mainline Mastodon, although some forks may do otherwise

This information should be available in the response to https://docs.joinmastodon.org/methods/instance/#v2.

It's not.

For comparison, the maximum number of featured tags an account can have is included (https://docs.joinmastodon.org/entities/Instance/#max_featured_tags). So adding an entry configuration[accounts][max_pinned_statuses] seems sensible.

Specifications

Issue in Mastodon 00ec439 (HEAD, at the time of writing this)

[imskr]

Can I work on this? @andypiper

[andypiper]

I'm only triaging and categorising issues right now, I have no objection to folks choosing to pick this up as a future addition but I'm unlikely to be the person to test or merge.