Example in `find_modules()` documentation is wrong

[vkarak]

This code listing in the documentation here is wrong:

my_find_modules = functools.partial(find_modules, environ_mapping={
    r'.*CrayGNU.*': {'PrgEnv-gnu'},
    r'.*CrayIntel.*': {'PrgEnv-intel'},
    r'.*CrayCCE.*': {'PrgEnv-cray'}
})

It should be

my_find_modules = functools.partial(find_modules, environ_mapping={
    r'.*CrayGNU.*': 'PrgEnv-gnu',
    r'.*CrayIntel.*': 'PrgEnv-intel',
    r'.*CrayCCE.*': 'PrgEnv-cray'
})

Otherwise you get a TypeError.