chsh, chpass: add pages; pages/linux/chsh: update page (#12160)

* chpass, chsh: add page for {Free,Net,Open}BSD and update common page

* pages.*BSD: add aliases for chpass

* chpass: add page for osx

pages/osx/chpass.md

@@ -0,0 +1,26 @@
+# chpass
+
+> Add or change user database information, including login shell and password.
+> NOTE: it's not possible to change the user's password on Open Directory systems, use `passwd` instead.
+> See also: `passwd`.
+> More information: <https://man.freebsd.org/cgi/man.cgi?chpass>.
+
+- Add or change user database information for the current user interactively:
+
+`su -c chpass`
+
+- Set a specific login [s]hell for the current user:
+
+`chpass -s {{path/to/shell}}`
+
+- Set a login [s]hell for a specific user:
+
+`chpass -s {{path/to/shell}} {{username}}`
+
+- Edit the user record on the directory node at the given [l]ocation:
+
+`chpass -l {{location}} -s {{path/to/shell}} {{username}}`
+
+- Use the given [u]sername when authenticating to the directory node containing the user:
+
+`chpass -u {{authname}} -s {{path/to/shell}} {{username}}`