Update README.md

Re omeka/omeka-s-enduser#207
Fix for omeka/omeka-s-enduser#145

README.md

@@ -2,11 +2,42 @@
 
 Create custom vocabularies and add them as data types to your resource templates.
 
+The Custom Vocab module allows you to create a controlled vocabulary and add it to a specific property in a resource template. When using that template for an item, the property will load with a dropdown limited to the options of the controlled vocabulary, rather than a text entry box.
+
+For example, you may want to create an institution-specific list of locations that correspond to different collections on your campus, or a controlled list of people or places related to your holdings. This can help reduce typos and name variations, and can allow you to offer [metadata browsing](https://omeka.org/s/modules/MetadataBrowse/) for more fields.
+
+Custom Vocab is available to users who are at the Editor role and above.
+
+A custom vocabulary can be imported from another Omeka installation, or exported to another installation.
+
+You can set the controlled vocabulary terms to a list of entered terms, to a list of existing items, or to a list of external URIs with or without labels:
+
+- Terms: a list of plain-text terms, one word or phrase per line. This populates the property as text.
+- Items: a drop-down of Item Sets in your Omeka S installation. Choosing one of these will create a custom vocab populated by items from that item set. When used, the property is populated as an Omeka Resource, not text.
+- URIs: a list of URIs with or without labels, one URI per line. To include a label, add a space and the label after the URI (for example, "https://youromekainstall.org/item/1119 Canada"). When used, the property will populate as a link to the external resource.
+
+Custom Vocabularies are applied through resource templates. When you are editing the template:
+
+- Add the property to which you want to apply the Custom Vocab.
+- Edit the property.
+- In the drawer which opens on the right, go to the Other options section and find the Data type dropdown.
+- Scroll through the dropdown and select the Custom Vocabulary you want to use.
+- Click set changes at the bottom of the drawer.
+
+Be sure to save your changes. 
+
+When this Resource Template is used in an Item or Item Set, the designated properties will always load as a drop down menu with the values from the custom vocabulary.
+
 See the [Omeka S user manual](http://omeka.org/s/docs/user-manual/modules/customvocab/) for user documentation.
 
-## Installation
+# For developers
+
+## Accessing Custom Vocabs through the API
+
+If you are a developer trying to access the custom vocabulary list through the API, the end points are the following:
 
-See general end user documentation for [Installing a module](http://omeka.org/s/docs/user-manual/modules/#installing-modules)
+- List of custom vocabularies are at `/api/custom_vocabs`
+- The details of a specific custom vocabulary is at `/api/custom_vocabs/<id>`
 
 # Copyright