doc: Add matrix expressions to docstrings (#756)

* Add matrix expressions to docstrings

* linter

* fix r-strings

* Capitalize H gate

* Rename theta->phi

* Address comments

* Update src/braket/circuits/gates.py

Co-authored-by: Ryan Shaffer <[email protected]>

* add matrices to subrountines

* Remove [Registers this function into the circuit class] line from docstrings

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Co-authored-by: Abe Coull <[email protected]>
Co-authored-by: Cody Wang <[email protected]>
Co-authored-by: Ryan Shaffer <[email protected]>
Co-authored-by: Abe Coull <[email protected]>
Co-authored-by: Aaron Berdy <[email protected]>