fix(ingest): hide main github readme from docs site

[hsheth2]

Will fix search and some SEO issues.

Checklist

• [x] The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• [ ] Links to related issues (if applicable)
• [ ] Tests for the changes have been added/updated (if applicable)
• [x] Docs related to the changes have been added/updated (if applicable). If a new feature has been added a Usage Guide has been added for the same.
• [ ] For any breaking change/potential downtime/deprecation/big changes an entry has been made in Updating DataHub

[github-actions[bot]]

Unit Test Results (metadata ingestion)

       8 files         8 suites   1h 1m 36s :stopwatch:    719 tests    715 :heavy_check_mark: 3 :zzz: 1 :x: 1 440 runs  1 433 :heavy_check_mark: 6 :zzz: 1 :x:

For more details on these failures, see this check.

Results for commit 57aa1a5b.

:recycle: This comment has been updated with latest results.

[github-actions[bot]]

Unit Test Results (build & test)

584 tests   580 :heavy_check_mark:  13m 25s :stopwatch: 143 suites      4 :zzz: 143 files        0 :x:

Results for commit 57aa1a5b.

:recycle: This comment has been updated with latest results.

[shirshanka]

@hsheth2 : is this still an active PR?

[hsheth2]

Yep - just updated it, and will merge it when CI is green.

[hsheth2]

We'll need to think about what to do with our README in a bit more detail.