git-flow-avh: update caveats per wiki

Closes #17451.

Signed-off-by: Misty De Meo <mistydemeo@gmail.com>
Groovy 2.1.0

Closes #17453.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
skipfish 2.10

Closes #17449.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>