docs(guidelines): add dependencies guidelines

[haddasbronfman]

Which problem is this PR solving?

After reading the discussion on #3847 and consulting other maintainers, I thought it would be good to write dependency guidelines.

Short description of the changes

Add GUIDELINES.md file. Currently contain only dependency guidelines.

[codecov]

Codecov Report

Merging #4040 (2a3a684) into main (5259a0b) will decrease coverage by 1.86%.
The diff coverage is n/a.

❗ Current head 2a3a684 differs from pull request most recent head 04358a3. Consider uploading reports for the commit 04358a3 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4040      +/-   ##
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- Coverage   92.37%   90.52%   -1.86%     
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  Files         321      159     -162     
  Lines        9273     3756    -5517     
  Branches     1970      835    -1135     
==========================================
- Hits         8566     3400    -5166     
+ Misses        707      356     -351     

see 167 files with indirect coverage changes

[pichlermarc]

Thanks for working on this 🙂
I've made some suggestions, no need to apply them all, feel free to change and adapt what fits 🙂

[pichlermarc]

Thanks for taking care of this 🙂

[legendecas]

The guidelines look good to me!

However, we have lots of files in the root directory already. It might be a good alternative to put the guideline in https://github.com/open-telemetry/opentelemetry-js/tree/main/doc.