User guide references deprecated `check` function

The [namespace docs state](https://funcool.github.io/buddy-hashers/latest/buddy.hashers.html) clearly that `buddy.hashers/check` "Should be considered as DEPRECATED" in preference of `buddy.hashers/verify`.

In [the User Guide](https://funcool.github.io/buddy-hashers/latest/user-guide.html), the examples correctly use `verify`, but other parts of the text contain references to `check`, which in both cases are vestigial and incorrect.

Instance 1:

> Hashers module consists in two public functions: derive and check and both them are located on buddy.hashers namespace.

Instance 2:

> Some times you don’t want to use all the supported algorithms and you only want to use a own set of algorithms in the password check process. That can be done passing additional parameter to the check function:

This is followed by an example using `verify` instead of `check`.

I'd be happy to contribute a pull request if that is welcome.

Open the User Guide linked in the issue and search for the two prose references to `check`. Update those references to `verify`, while preserving the existing examples, then review the page alongside the namespace documentation to confirm no deprecated function references remain in the guide.

Written by the indexing model from the issue text.