Create gsoc-contributor-guidance.md

[anjula-sack]

To suggest a change to the Handbook, please review the Handbook Guidlines section.

Purpose:

The purpose of this PR is to fix #

Related to:

Please provide a brief explanation for this change:

Preview Link:

https://pr-37-sef-handbook.surge.sh/

Please indicate the types of revisions being suggested for the Handbook (please check all that apply):

• Small improvement (typos, clarifications, etc.)
• Adding a new section
• Modifying existing section
• Documenting a new process
• Adding a new page or directory
• Other

Author Checklist

• Provided a concise title for the PR
• Provided a brief explanation for this change (Say why not just what)
  • (Attach screenshots, Slack conversations, etc. as necessary)
• Indicated the types of changes included in this PR
• Verified that no confidential data is in this PR
• Posted an update in #handbook channel
• If the changes affect team members, or warrant an announcement in another way, please consider posting an update in #general channel