Replace 'treeish' in documentation and comments with 'tree-ish' to
match gitglossary(7).
The only remaining instances of 'treeish' are:
* variable, function, and macro names
* "(also treeish)" in the definition of tree-ish in gitglossary(7)
Signed-off-by: Richard Hansen <rhansen@bbn.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
