Fix meeting and typos

[BrianPetkovsek]

Description

This pull request updates the CONTRIBUTING.md file to improve clarity and provide more accurate information for contributors. The changes fix typos and update references to community resources.

Fixes:
Community resources and meeting information:

• Updated the link to the OpenTelemetry community calendar to the updated url.

• Fixed a typo in the instructions, changing "Please for this repo in a personal Github account instead." to "Please fork this repo in a personal Github account instead.".

• Fixed a typo in the instructions, changing "See to the community membership document" to "See the community membership document".

Type of change

Please delete options that are not relevant.

• [ x] Bug fix (non-breaking change which fixes an issue)
• [ x] This change requires a documentation update

Checklist:

• [ x] Followed the style guidelines of this project
• Changelogs have been updated
• [ x] Documentation has been updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: BrianPetkovsek / name: Brian Petkovsek (0f80e14, e4a601d)

[xrmx]

Thanks!