Add "Known problems" section to needless_borrow documentation

[smoelius]

While this PR doesn't fix the issue in #11142, it at least communicates that this is a known limitation.

r? @Jarcho

changelog: Add "Known problems" section to needless_borrow documentation

[Jarcho]

Thank you. @bors r+

Just as an aside, GitHub's overzealous automatic issue linking for PR's triggers whenever you type fix #number. Please try to be careful when wording PR descriptions to workaround GitHub's issues. fixes, fixed, close, closes, closed, resolve, resolves, and resolved all trigger the same thing.

[bors]

📌 Commit 050b714 has been approved by Jarcho

It is now in the queue for this repository.

[bors]

⌛ Testing commit 050b714 with merge b10a0aa...

[smoelius]

Just as an aside, GitHub's overzealous automatic issue linking for PR's triggers whenever you type fix #number. Please try to be careful when wording PR descriptions to workaround GitHub's issues. fixes, fixed, close, closes, closed, resolve, resolves, and resolved all trigger the same thing.

😬 My sincerest apologies. Thank you for fixing that.

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: Jarcho
Pushing b10a0aa to master...