Clarified docs around creating and invoking custom templates. Closes issue #120

templates/README.md

@@ -0,0 +1,20 @@
+To create or use your own template, create a folder, and give it the name of your template, for example "mycooltemplate". Within this folder create a file named "publish.js". That file must define a global method named "publish". For example:
+
+````javascript
+/**
+ * Turn the data about your docs into file output.
+ * @global
+ * @param {TAFFY} data - A TaffyDB collection representing
+ *                       all the symbols documented in your code.
+ * @param {object} opts - An object with options information.
+ */
+function publish(data, opts) {
+    // do stuff here to generate your output files
+}
+````
+
+To invoke JSDoc 3 with your own template, use the `-t` command line option, giving it the path to your template folder.
+
+````
+./jsdoc mycode.js -t /path/to/mycooltemplate
+````