Clarify example requirements

Author: gummif

README.md

@@ -41,16 +41,17 @@ Supported platforms
 
 Examples
 ========
+This example requires at least C++11.
 ```c++
 #include <string>
 #include <zmq.hpp>
+
 int main()
 {
-   zmq::context_t ctx;
-   zmq::socket_t sock(ctx, zmq::socket_type::push);
-   sock.bind("inproc://test");
-   const std::string_view m = "Hello, world";
-   sock.send(zmq::buffer(m), zmq::send_flags::dontwait);
+    zmq::context_t ctx;
+    zmq::socket_t sock(ctx, zmq::socket_type::push);
+    sock.bind("inproc://test");
+    sock.send(zmq::str_buffer("Hello, world"), zmq::send_flags::dontwait);
 }
 ```
 

tests/socket.cpp

@@ -71,8 +71,7 @@ TEST_CASE("socket readme example", "[socket]")
     zmq::context_t ctx;
     zmq::socket_t sock(ctx, zmq::socket_type::push);
     sock.bind("inproc://test");
-    const std::string m = "Hello, world";
-    sock.send(zmq::buffer(m), zmq::send_flags::dontwait);
+    sock.send(zmq::str_buffer("Hello, world"), zmq::send_flags::dontwait);
 }
 #endif