chore(docs): add release note guidelines

[Yun-Kim]

Description

This change adds a new section for release note guidelines, and a new reno template which should allow more consistency in our release notes moving forward.

Checklist

• Add additional sections for feat and fix pull requests.
• Library documentation and/or Datadog's documentation site is updated. Link to doc PR in description.

Motivation

Design

Testing strategy

Relevant issue(s)

Testing strategy

Reviewer Checklist

• Title is accurate.
• Description motivates each change.
• No unnecessary changes were introduced in this PR.
• Avoid breaking API changes unless absolutely necessary.
• Tests provided or description of manual testing performed is included in the code or PR.
• Release note has been added for fixes and features, or else changelog/no-changelog label added.
• All relevant GitHub issues are correctly linked.
• Backports are identified and tagged with Mergifyio.

[Kyle-Verhoog]

should we also update the PR checklist with a link to this new documentation? (the link will probably be broken until we do the next release)

[Kyle-Verhoog]

🚢 it!!

[mabdinur]

🥳

[majorgreys]

If we want this to be the same scope used in the conventional commits, we need them to conform to the same format, which means lower case and shorter. But then we might end up making it harder for someone skimming release notes for the changes related to their use of the library.

[codecov-commenter]

Codecov Report

Merging #4551 (e33c90c) into 1.x (e82c3d4) will increase coverage by 0.00%.
The diff coverage is n/a.

❗ Current head e33c90c differs from pull request most recent head eeb0e95. Consider uploading reports for the commit eeb0e95 to get more accurate results

@@           Coverage Diff           @@
##              1.x    #4551   +/-   ##
=======================================
  Coverage   77.95%   77.95%           
=======================================
  Files         759      759           
  Lines       60125    60125           
=======================================
+ Hits        46872    46873    +1     
+ Misses      13253    13252    -1     

Impacted Files	Coverage Δ
tests/utils.py	90.35% <0.00%> (-0.24%)	⬇️
ddtrace/internal/telemetry/writer.py	77.24% <0.00%> (+0.68%)	⬆️
ddtrace/internal/remoteconfig/worker.py	100.00% <0.00%> (+4.34%)	⬆️

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