User Guide: Add instructions for searching Collection by session id

[kgrons]

Since the data elements in the left Metadata panel in a Collection Index are searchable via the search bar above the links, it would be helpful to add something like the following to the user guide:

Search Collection Index

• Find all links from a session in a Collection by typing session: (session + colon, no spaces)

• After typing session: enter the session ID (can be found in the left Metadata panel after selecting one of the pages).

• Sample entry session id: mnaxml2zbycz2fng