aminya-project-options usage typo

There's a typo for the usage instructions for aminya-project-options

it should be this (note, no .cmake suffix)
```
The package aminya-project-options provides modules:

    find_package(aminya-project-options REQUIRED)
    # More modules can refer to <https://github.com/aminya/project_options>.
    include(aminya-project-options/Index)
```