docs: add RTL support section

[mohSalah66]

there is no Right to left Support in the official documentation website and i searched everywhere i found someone mentioned RTL Support by using the $mdBiDirectionalProvider but there is no such provider in angular material.
see the question in stackoverflow
Please point out the RTL Support if exists.
thank you in advance.
best regards.

[ThomasBurleson]

@EladBezalel - can you respond to @Touti1991 interest. Our docs, solutions, and pending PRs?

And then let's close this issue as we other issues/PRs that address this need.

[EladBezalel]

We should add section to explain how to enable RTL mode