N-10 [Oval] Typographical Errors

[md0x]

Fixes the following issue reported in the Oval Incremental Audit:

Throughout the codebase, there are several instances of typographical errors:
In the PermissionProxy.sol file:
In line 8, the word "allows" should be removed.
In line 10, the word "oval" should be written starting with a capital letter.
In the MutableUnlockersController.sol file:
In line 8, "can be change" should be "can be changed".
Consider fixing all instances of typographical errors in order to improve the readability of the
codebase.

[linear]

UMA-2654 N-10 [Oval] Typographical Errors