Update CONTRIBUTING.md

[xjwllmsx]

Description

This PR corrects a typo and grammatical mistake in CONTRIBUTING.md

Related Tickets & Documents

Fixes #69

Mobile & Desktop Screenshots/Recordings

Original (branch main):

After PR:

Steps to QA

• Navigate to https://github.com/xjwllmsx/.github/blob/main/CONTRIBUTING.md
  • Note the second to last sentence reads: "If you would like to contribute to the project for the first time, please consider checking the bug or good first issue labels."
  • Note that the original second to last sentence reads: "If you would like to contribute to the project for the first time, please consider joining checking the bug or good first issue labels."

Tier (staff will fill in)

• Tier 1
• Tier 2
• Tier 3
• Tier 4

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