Fix: merge augmentation function docs

See #200

Merge the augmentations of the same target, as if they were defined
in the same augmentation.

The line and documentation of the augmentation itself are the ones
of the first augmentation declared, since merging docs can results
in not meaningful text.
Code formating
Merge pull request #201 from yloiseau/bug/DocWhenMoreAugment

Fix: merge augmentation function docs