fix: replace "Github" with "GitHub"

[xlgmokha]

Why:

The brand name GitHub uses an upper case letter H. This is the same for all languages.

What's being changed:

This change updates usages of Github to GitHub to match the brand.

Check off the following:

• I have reviewed my changes in staging (look for "Automatically generated comment" and click Modified to view your latest changes).
• For content changes, I have completed the self-review checklist.

Writer impact (This section is for GitHub staff members only):

• This pull request impacts the contribution experience
  • I have added the 'writer impact' label
  • I have added a description and/or a video demo of the changes below (e.g. a "before and after video")

[github-actions]

👋 Hey there spelunker. It looks like you've modified some files that we can't accept as contributions. The complete list of files we can't accept are:
.devcontainer/**
.github/actions-scripts/**
.github/workflows/**
.github/CODEOWNERS
assets/fonts/**
data/graphql/**
Dockerfile*
lib/graphql/**
lib/redirects/**
lib/rest/**
lib/webhooks/**
lib/search/indexes/**
package*.json
scripts/**
translations/**
content/actions/deployment/security-hardening-your-deployments/**

You'll need to revert all of the files you changed in that list using GitHub Desktop or git checkout origin/main <file name>. Once you get those files reverted, we can continue with the review process.

[ramyaparimi]

@xlgmokha
Thanks for opening this! Unfortunately, we are not able to accept changes for translated content. Our translation process involves an integration with an external service at crowdin.com, where all translation activity happens. We hope to eventually open up the translation process to the open-source community, but we're not there yet.

See https://github.com/github/docs/blob/main/contributing/types-of-contributions.md#earth_asia-translations.