Update CONTRIBUTING.md for policy against too large Gerrit Patches

[demonCoder95]

Problem description (if applicable)
Currently, there's quite a bit of changes in Gerrit that are just TOO LARGE; 1000s of lines in dozens of files. All of these are providing too many components/features within a single change. This makes the review process extremely challenging, and also goes against the opendev development guidelines.

Proposed change
I suggest a note in the CONTRIBUTING.md file for awareness against this. Smaller well-defined changes in Gerrit will improve as well as facilitate code review!

Potential impacts
N/A

[demonCoder95]

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[airshipbot]

Related Change #739263

Subject: Guideline against very large Gerrit Changes
Link: https://review.opendev.org/739263
Status: MERGED
Owner: Noor Muhammad Malik (noormuhammadmalik95@gmail.com)

This change will close this issue when merged.

Approvals

Code-Review
+2 Ian Howell
+2 Alexander Hughes
Verified
+2 Zuul
Workflow
+1 Alexander Hughes

Last Updated: 2020-07-06 19:00:04 CDT

[airshipbot]

The Change that closes this issue was merged.