LP#1701001: add release notes

LP#1701001: add release notes

Here is the test plan for the feature:

[1] In the web staff client, perform a catalog search. From search
    results, choose Place Hold.
[2] In the form that displays, click the 'Patron Search' button.
[3] Verify that a modal with a patron search form is displayed.
[4] Search for a patron, then select one and click the 'Select'
    button.
[5] Verify that the patron's barcode is inserted into the patron
    barcode input.
[6] Verify that submitting the form successfully places the hold.
[7] Verify that the feature works from a bib record details page.
[8] Verify that the Patron Search button does not show up when
    using the place hold form in the public catalog.
[9] Verify that normal patron search, retrieval, and registration
    functionality continues to work, as this patch series does some
    refactoring to create a reusable Angular patron search service
    and templates.

Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>
Signed-off-by: Chris Sharp <csharp@georgialibraries.org>