Docs: Remove documentation for useNestedStrict

[mark-langer]

Summary
This option has been deprecated in 6.0. It doesn't show up in code files any more when searching the repo, so I guess removing the docs is a good thing to do.

If you're making a change to documentation, do not modify a .html file directly. Instead find the corresponding .pug file or test case in the test/docs directory.

The modified file is the only place the Github search finds the option useNestedStrict, therefore I edited that directly. Maybe it can be updated by recompiling the docs as well?

Examples
None

[AbdelrahmanHafez]

LGTM, thanks 👍

[vkarpov15]

Thanks 👍