Fix typo in README

Spotted by @soxofaan

Author: ncoghlan

README.rst

@@ -49,7 +49,7 @@ To build the guide, run the following bash command in the source folder::
 
 After the process has completed you can find the HTML output in the
 ``./build/html`` directory. You can open the ``index.html`` file to view the
-guide in web broswer, but it's recommended to serve the guide using an HTTP
+guide in web browser, but it's recommended to serve the guide using an HTTP
 server.
 
 Serving the guide using a local HTTP server