Fix improperly formatted docstring

Change the docstring of chompPrefix to prevent the error
"doc comment parse failed" that was raised by some version of
haddock while generating the documentation for this function.

Signed-off-by: Michele Tartara <mtartara@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>
(cherry picked from commit 94042ae4)

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Bernardo Dal Seno <bdalseno@google.com>