Documentation Update Needed

In Pipes.Safe you have this comment:

```
{-| This module provides an orphan 'MonadCatch' instance for 'Proxy' of the
form:
> instance (MonadCatch m, MonadIO m) => MonadCatch (Proxy a' a b' b m) where
```

However, the only orphan instance I can find in that file (or re-exported by that file) is MonadMask for Proxy:

```
instance (MonadMask m, MonadIO m) => MonadMask (Proxy a' a b' b m) where
mask = liftMask mask

uninterruptibleMask = liftMask uninterruptibleMask

#if MIN_VERSION_exceptions(0,10,0)
generalBracket acquire release_ use = mask $ \unmasked -> do
a <- acquire
let action = do
b <- use a
return (ExitCaseSuccess b, ExitCaseSuccess_ b)
let handler e = return (ExitCaseException e, ExitCaseException_ e)
(exitCase, exitCase_) <- unmasked action `catch` handler
c <- release_ a exitCase
case exitCase_ of
ExitCaseException_ e -> throwM e
ExitCaseSuccess_ b -> return (b, c)
```

If this is a mistake I can make a pull request with the updated documentation.

Start by locating the Pipes.Safe module documentation comment quoted in the issue and compare its MonadCatch description with the MonadMask instance shown there. Update the inaccurate wording to match the documented instance, then build or generate the documentation to confirm the corrected text.

Written by the indexing model from the issue text.