Switch to pkgdown Bootstrap 5 template

[eitsupi]

Close #5503

The switch to bs5 will allow for search within the site, which will be very useful for users.

It will look like the following and a search window will be added in the upper right corner.

This PR is a small change to the pkgdown site configuration only; there are no changes to the document itself or to the R code.

How to test?

1. Pull this branch.
2. Run the pkgdown::build_site() function on the project root.
3. The website code will be generated in the ./docs dir.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ac57606) 97.46% compared to head (e3d9900) 97.46%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5505   +/-   ##
=======================================
  Coverage   97.46%   97.46%           
=======================================
  Files          80       80           
  Lines       14822    14822           
=======================================
  Hits        14447    14447           
  Misses        375      375           

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[eitsupi]

@jangorecki Could you take a look at this?

[jangorecki]

LGTM

[eitsupi]

Could you merge this?
I think this is useful.

[jangorecki]

Yes, we will merge. We are now on track to get data.table code contribution running smoothly. You may expect to wait for 1.15.99 to have it merged. Please see #5385 for justification.

[jangorecki]

Any idea why this is not the default in pkgdown?

[eitsupi]

Any idea why this is not the default in pkgdown?

This is a breaking change and we just need to opt in, check the pkgdown release notes.

[eitsupi]

Anyway, this is not a major change and I see no reason why it cannot be merged immediately.
At the moment the documentation for data.table is very difficult for beginners to read as it is not searchable.

[jangorecki]

Website looks much better on the mobile browser now

[eitsupi]

Great! Thanks for merging this.