update api doc example for client and add panic info for connection_info

awc/src/lib.rs

@@ -1,7 +1,7 @@
 //! An HTTP Client
 //!
 //! ```rust
-//! # use futures::future::{Future, lazy};
+//! use futures::future::{lazy, Future};
 //! use actix_rt::System;
 //! use awc::Client;
 //!

src/request.rs

@@ -186,6 +186,9 @@ impl HttpRequest {
     }
 
     /// Get *ConnectionInfo* for the current request.
+    ///
+    /// This method panics if request's extensions container is already
+    /// borrowed.
     #[inline]
     pub fn connection_info(&self) -> Ref<ConnectionInfo> {
         ConnectionInfo::get(self.head(), &*self.app_config())