Clarify parameter usage

content/v3.md

@@ -40,6 +40,29 @@ All timestamps are returned in ISO 8601 format:
 
     YYYY-MM-DDTHH:MM:SSZ
 
+## Parameters
+
+Many API methods take optional parameters. For GET requests, any parameters not
+specified as a segment in the path can be passed as an HTTP query string
+parameter:
+
+<pre class="terminal">
+$ curl -i "https://api.github.com/repos/mojombo/jekyll/issues?state=closed"
+</pre>
+
+In this example, the 'mojombo' and 'jekyll' values are provided for the `:user`
+and `:repo` parameters in the path while `:state` is passed in the query
+string.
+
+For POST requests, parameters not included in the URL should be encoded as JSON
+with a Content-Type of 'application/x-www-form-urlencoded':
+
+<pre class="terminal">
+$ curl -i -u username -d '{"scopes":["public_repo"]}' https://api.github.com/authorizations
+</pre>
+
+
+
 ## Client Errors
 
 There are three possible types of client errors on API calls that