fix readOnly for select

Author: jamesej

.gitignore

@@ -1,2 +1,3 @@
 node_modules
 /lib
+/build

README.md

@@ -167,6 +167,7 @@ JSON schema is an extremely powerful descriptive language and this package while
 | generic: description | Description is rendered as part of the label and can be styled differently |
 | generic: default | Not supported. Normally a default would be set on the initial value object passed to the form. |
 | generic: enum | A string-typed schema with an enum property will be rendered by default as a drop-down list i.e. an HTML select |
+| generic: readOnly | If true, the value should not be editable just displayed |
 | generic: const | Only implemented as validation: for use in conditionals only. |
 | generic: editor | NON-STANDARD. This custom keyword which has no effect on validation allows definition of an editor to be used to render this schema. See Built-in editors below for a list of possibilities. |
 | combiner: allOf | A conjoin (see below) is done between the list of subschemas given and the main schema. Validation is also applied |