Fix GitHub capitalization in README

[Wenjunyun123]

Summary:

• Updates README references from Github to GitHub.

Testing:

• Verified the README uses GitHub capitalization for the touched references.
• Documentation-only change; docs were not rebuilt.

AI assistance: This documentation fix was prepared with AI assistance and reviewed before submission.

[arnopo]

Hello @Wenjunyun123

Thanks for this update, it looks good to me. Could you just update the commit message
we expect that the commit message contains:

• a title
• a description of the problem and the solution ( here should be very short for your commit)
• your signed-off