docs($httpProvider): add documentation

src/ng/http.js

@@ -83,14 +83,40 @@ function isSuccess(status) {
 }
 
 
+/**
+ * @ngdoc provider
+ * @name $httpProvider
+ * @description
+ * Use `$httpProvider` to change the default behavior of the {@link ng.$http $http} service.
+ * */
 function $HttpProvider() {
   var JSON_START = /^\s*(\[|\{[^\{])/,
       JSON_END = /[\}\]]\s*$/,
       PROTECTION_PREFIX = /^\)\]\}',?\n/,
       CONTENT_TYPE_APPLICATION_JSON = {'Content-Type': 'application/json;charset=utf-8'};
 
+  /**
+   * @ngdoc property
+   * @name $httpProvider#defaults
+   * @description
+   *
+   * Object containing default values for all {@link ng.$http $http} requests.
+   *
+   * - **`defaults.xsrfCookieName`** - {string} - Name of cookie containing the XSRF token.
+   * Defaults value is `'XSRF-TOKEN'`.
+   *
+   * - **`defaults.xsrfHeaderName`** - {string} - Name of HTTP header to populate with the
+   * XSRF token. Defaults value is `'X-XSRF-TOKEN'`.
+   *
+   * - **`defaults.headers`** - {Object} - Default headers for all $http requests.
+   * Refer to {@link ng.$http#setting-http-headers $http} for documentation on
+   * setting default headers.
+   *     - **`defaults.headers.common`**
+   *     - **`defaults.headers.post`**
+   *     - **`defaults.headers.put`**
+   *     - **`defaults.headers.patch`**
+   * */
   var defaults = this.defaults = {
-    // transform incoming response data
     transformResponse: [function(data) {
       if (isString(data)) {
         // strip json vulnerability protection prefix
@@ -106,7 +132,6 @@ function $HttpProvider() {
       return isObject(d) && !isFile(d) && !isBlob(d) ? toJson(d) : d;
     }],
 
-    // default headers
     headers: {
       common: {
         'Accept': 'application/json, text/plain, */*'