Fix typo

Author: mgbckr

README.rst

@@ -420,7 +420,7 @@ Currently, the backend can be set via the CLI
 
     $ python -m memory_profiler --backend psutil my_script.py
 
-and is explosed by the API
+and is exposed by the API
 
     >>> from memory_profiler import memory_usage
     >>> mem_usage = memory_usage(-1, interval=.2, timeout=1, backend="psutil")
@@ -504,6 +504,8 @@ cleanup.
 
 `Juan Luis Cano <https://github.com/Juanlu001>`_ modernized the infrastructure and helped with various things.
 
+`Martin Becker <https://github.com/mgbckr>`_ added PSS and USS tracking via the psutil backend.
+
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  License
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