add doc

docs/api_http

@@ -0,0 +1,29 @@
+	mg_set_request_handler(ctx,
+	                       "/form",
+	                       FileHandler,
+	                       (void *)"../../test/form.html");
+
+	mg_set_request_handler(ctx, EXAMPLE_URI, ExampleHandler, 0);
+	mg_set_request_handler(ctx, EXIT_URI, ExitHandler, 0);
+    
+    /* mg_set_request_handler
+   Sets or removes a URI mapping for a request handler.
+   This function uses mg_lock_context internally.
+   URI's are ordered and prefixed URI's are supported. For example,
+   consider two URIs: /a/b and /a
+           /a   matches /a
+           /a/b matches /a/b
+           /a/c matches /a
+   Parameters:
+      ctx: server context
+      uri: the URI (exact or pattern) for the handler
+      handler: the callback handler to use when the URI is requested.
+               If NULL, an already registered handler for this URI will
+               be removed.
+               The URI used to remove a handler must match exactly the
+               one used to register it (not only a pattern match).
+      cbdata: the callback data to give to the handler when it is called. */
+CIVETWEB_API void mg_set_request_handler(struct mg_context *ctx,
+                                         const char *uri,
+                                         mg_request_handler handler,
+                                         void *cbdata);