Updates link text for source on record pages

Why are these changes being introduced:

* As currently displayed, the full record view Source links could be
  interpreted as going to the root of the source repository rather than
  the individual record within the repository and thus might seem of
  little value to end users.

Relevant ticket(s):

* https://mitlibraries.atlassian.net/browse/RDI-240

How does this address that need:

* Provides a clearer link label to the Item record in the source

Author: JPrevost

app/views/record/_record.html.erb

@@ -59,7 +59,7 @@
     <h3 class="section-title">Links</h3>
     <ul class="list-links">
       <li>
-        <span class="label">Source:</span> <%= link_to(@record['source'], @record['sourceLink']) %>
+        <%= link_to("Item record", @record['sourceLink']) %> in <%= @record['source'] %>
       </li>
 
       <% if @record['links'].present? %>