Docs 2.6: Update screens for register/edit patron

Update screenshots and wording to reflect new "Update Expire Date" button.

Signed-off-by: Remington Steed <rjs7@calvin.edu>
Docs: Update commands for authority importing script

The tools used for importing authority records from the command line have
been modified since the original docs were written. Testing revealed these
changes, which are reflected in this commit.

Signed-off-by: Remington Steed <rjs7@calvin.edu>
Docs: Fix patron registration screenshot

The previously committed screenshot contains site-specific information
which is not broadly beneficial. This commit replaces it with a more
generic screenshot.

Signed-off-by: Remington Steed <rjs7@calvin.edu>