Fixed heading structure to maintain symmetry

[roshnaeem]

Description

On the Contributing page, the links in the bullet points are not on the same level. Heading-1 should only be the title of the page, but contributing_prs.md consisted of a lot of first-level headings. Fixed the heading levels to maintain the symmetry.

[OriolAbril]

I think it would be best to do it as part of #1903, because there the hierarchy is also modified. Here or there works fine by me as the end result will be the same, but doing two separate PRs will probably mean rebases and git conficts on your end

[codecov]

Codecov Report

Merging #1936 (872cc5f) into main (f5977ca) will not change coverage.
The diff coverage is n/a.

❗ Current head 872cc5f differs from pull request most recent head 738cd47. Consider uploading reports for the commit 738cd47 to get more accurate results

@@           Coverage Diff           @@
##             main    #1936   +/-   ##
=======================================
  Coverage   91.72%   91.72%           
=======================================
  Files         116      116           
  Lines       12362    12362           
=======================================
  Hits        11339    11339           
  Misses       1023     1023           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f5977ca...738cd47. Read the comment docs.

[roshnaeem]

It is fine, you can merge it, I'll rebase the other PR with main.