* doc/org-manual.org: Add `:tree-type month' option for capture
templates.
* lisp/org-capture.el (org-capture-set-target-location): Add
`:tree-type month' option to capture templates to group entries by
month.
* lisp/org-datetree.el (org-datetree-find-month-create): Add
`org-datetree-find-month-create' function to add datetree entries
grouped by month.
* testing/lisp/test-org-datetree.el
(test-org-datetree/find-month-create): Add test for new function.
a410413be8