[ADF-1586] Added docs for services (#2619)

* [ADF-1586] Added docs for services

* [ADF-1586] Removed model definitions from docs

docs/bpm-user.model.md

@@ -0,0 +1,24 @@
+# Bpm User model
+
+Contains information about a Process Services user.
+
+## Details
+
+Instances of this class are returned by the methods of the
+[Bpm User service](bpm-user.service.md). It implements the
+`UserRepresentation` interface, which is defined in the
+[Alfresco JS API]h(ttps://github.com/Alfresco/alfresco-js-api/blob/master/src/alfresco-activiti-rest-api/docs/UserRepresentation.md).
+
+Note that the Typescript class for this model is in active development;
+it is likely to change and so its properties are not listed here. For the
+latest version of the class, see the
+[source file](https://github.com/Alfresco/alfresco-ng2-components/blob/development/ng2-components/ng2-alfresco-userinfo/src/models/bpm-user.model.ts).
+
+<!-- Don't edit the See also section. Edit seeAlsoGraph.json and run config/generateSeeAlso.js -->
+<!-- seealso start -->
+## See also
+
+- [Bpm user service](bpm-user.service.md)
+- [Ecm user model](ecm-user.model.md)
+- [People process service](people-process.service.md)
+<!-- seealso end -->