[ADF-1586] Added docs for Core services (#2548)

docs/user-initial.pipe.md

@@ -0,0 +1,26 @@
+# User Initial pipe
+
+Takes the name fields of a UserProcessModel object and extracts and formats the initials.
+
+## Basic Usage
+
+```HTML
+<div>
+    Project Leader: {{ user | usernameInitials:"initialsClass" }}
+</div>
+```
+
+## Details
+
+The pipe gets the initial characters of the user's first and last names and
+concatenates them. The results are returned in an HTML &lt;div&gt; element.
+
+The first pipe parameter specifies an optional CSS class to add to the &lt;div&gt;
+element (eg, a background color is commonly used to emphasise initials). The
+second parameter is an optional delimiter to add between the initials.
+Both parameters default to empty strings.
+
+<!-- Don't edit the See also section. Edit seeAlsoGraph.json and run config/generateSeeAlso.js -->
+<!-- seealso start -->
+
+<!-- seealso end -->