Serials Docs: Update for new features in 2.5

Serials Docs: Update for new features in 2.5

This commit adds a "Notes" section to the chapter on Receiving, including
a subsection on using the new "alerts" feature in the receiving interface.
It also adds a new screenshot for the "Notes" section and updates two
screenshots that have changed in 2.5. Finally, this commit updates the
Serials Copy Template doc to reflect the new 2.5 Floating Groups feature.

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