feat(docs): add search functionality to docs site

[singhamit0002]

Feature Description

Hi Team,
Can we have filter/search functionality on left menu may be on top can have on input box and provide filter functionality

Use Case

Let say I have been landed to the URL - https://material.angular.io/components/table/examples
And I wanted to see the spinner component and I don't have idea where is spinner component and where to scroll the page.
In this case if I could see the search functionality would be very useful for me to search "Spinner" and then I can get the spinner component options.

Hence this additional feature will provide good experience to users. Thanks!!

[wagnermaciel]

Hijacking this idea to increase the scope. We should add a search bar to the top nav to be able to quickly search for guides, docs, etc. in the docs site (similar to https://angular.io/).

[lesteral]

Please do consider this - it would be decidedly more user friendly than the alternative of searching on GitHub.