docs: Remove announcements (the job posting is filled?)

[deyton]

I happened to click on the link, and I guess this posting is from 5 months ago 😄

Checklist

• I have made a material change to the repo (functionality, testing, spelling, grammar)
• I have read the [Contribution Guide] and my PR follows them.
• I updated my branch with the master branch.
  - [ ] I have added tests that prove my fix is effective or that my feature works
  - [ ] I have added necessary documentation about the functionality in the appropriate .md file
  - [ ] I have added in line documentation to the code I modified

Short description of what this PR does:

• Removes the announcements section from the readme, since its only contents was a job posting for a job that doesn't seem to be open according to the careers page

[SendGridDX]

All committers have signed the CLA.

[thinkingserious]

Hello @deyton,

Thanks again for the PR!

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Team SendGrid DX