Update documentation about installing locust

Locust version 1 and 2 seems now supported by transformer

Author: kartoch

README.rst

@@ -48,12 +48,9 @@ Install from PyPI::
 
    pip install har-transformer
 
-Note that the new major version of Locust (1.0 and up) is not yet supported.
-Please make sure you have a compatible Locust to run your locustfiles::
+Install Locust to run your locustfiles::
 
-   pip install locustio==0.14.6
-
-We hope to lift this restriction very soon!
+   pip install locust
 
 Usage
 =====