doc: fix type of http.request's agent option

doc/api/http.md

@@ -1500,34 +1500,37 @@ added: v0.3.6
 
 * `options` {Object}
   * `protocol` {String} Protocol to use. Defaults to `'http:'`.
-  * `host` {String} A domain name or IP address of the server to issue the request to.
-    Defaults to `'localhost'`.
-  * `hostname` {String} Alias for `host`. To support [`url.parse()`][] `hostname` is
-    preferred over `host`.
-  * `family` {Number} IP address family to use when resolving `host` and `hostname`.
-    Valid values are `4` or `6`. When unspecified, both IP v4 and v6 will be
-    used.
+  * `host` {String} A domain name or IP address of the server to issue the
+    request to. Defaults to `'localhost'`.
+  * `hostname` {String} Alias for `host`. To support [`url.parse()`][],
+    `hostname` is preferred over `host`.
+  * `family` {Number} IP address family to use when resolving `host` and
+    `hostname`. Valid values are `4` or `6`. When unspecified, both IP v4 and
+    v6 will be used.
   * `port` {Number} Port of remote server. Defaults to 80.
   * `localAddress` {String} Local interface to bind for network connections.
-  * `socketPath` {String} Unix Domain Socket (use one of host:port or socketPath).
-  * `method` {String} A string specifying the HTTP request method. Defaults to `'GET'`.
-  * `path` {String} Request path. Defaults to `'/'`. Should include query string if any.
-    E.G. `'/index.html?page=12'`. An exception is thrown when the request path
-    contains illegal characters. Currently, only spaces are rejected but that
-    may change in the future.
+  * `socketPath` {String} Unix Domain Socket (use one of host:port or
+    socketPath).
+  * `method` {String} A string specifying the HTTP request method. Defaults to
+    `'GET'`.
+  * `path` {String} Request path. Defaults to `'/'`. Should include query
+    string if any. E.G. `'/index.html?page=12'`. An exception is thrown when
+    the request path contains illegal characters. Currently, only spaces are
+    rejected but that may change in the future.
   * `headers` {Object} An object containing request headers.
   * `auth` {String} Basic authentication i.e. `'user:password'` to compute an
     Authorization header.
-  * `agent` {String} Controls [`Agent`][] behavior. When an Agent is used request will
-    default to `Connection: keep-alive`. Possible values:
+  * `agent` {http.Agent|Boolean} Controls [`Agent`][] behavior. When an Agent
+    is used request will default to `Connection: keep-alive`. Possible values:
    * `undefined` (default): use [`http.globalAgent`][] for this host and port.
    * `Agent` object: explicitly use the passed in `Agent`.
    * `false`: opts out of connection pooling with an Agent, defaults request to
      `Connection: close`.
-  * `createConnection` {Function} A function that produces a socket/stream to use for the
-    request when the `agent` option is not used. This can be used to avoid
-    creating a custom Agent class just to override the default `createConnection`
-    function. See [`agent.createConnection()`][] for more details.
+  * `createConnection` {Function} A function that produces a socket/stream to
+    use for the request when the `agent` option is not used. This can be used to
+    avoid creating a custom Agent class just to override the default
+    `createConnection` function. See [`agent.createConnection()`][] for more
+    details.
   * `timeout` {Integer}: A number specifying the socket timeout in milliseconds.
     This will set the timeout before the socket is connected.
 * `callback` {Function}