Documentation: Update upgrade instruction for 2.6.1

- Update location references for 2.6.1.
- Update database updates to include 2.6.1 update.
- Add a note regarding reingesting bib records after updates.

Signed-off-by: Robert Soulliere <robert.soulliere@mohawkcollege.ca>
Documentation: Upgrade instructions examples

This commit adds a note (with examples) about upgrading the database schema
across major versions. It also reformats a long line into multiple lines,
changes a NOTE to a TIP, makes a small correction, and replaces a repetitive
command with a short explanation.

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