Add method description

Author: khiga8

lib/utils/get-element-type.js

@@ -1,5 +1,12 @@
 const {elementType, getProp, getPropValue} = require('jsx-ast-utils')
 
+/*
+Allows custom component to be mapped to an element type.
+When a default is set, all instances of the component will be mapped to the default.
+If a prop determines the type, it can be specified with `props`.
+
+For now, we only support the mapping of one prop type to an element type, rather than combinations of props.
+*/
 function getElementType(context, node) {
   const {settings} = context
   const rawElement = elementType(node)