Update README.rst

Added Mike Purvis a.k.a mikepurvis to contributors list.

Author: queezythegreat

README.rst

@@ -86,6 +86,7 @@ I would like to thank the following people for contributing to **Arduino CMake**
 * Logan Engstrom (`meadowstream`_) 
 * Francisco Ramírez (`franramirez688`_)
 * Brendan Shillingford (`bshillingford`_)
+* Mike Purvis (`mikepurvis`_) 
 
 .. _Kernald: https://github.com/Kernald
 .. _jgoppert: https://github.com/jgoppert
@@ -105,6 +106,7 @@ I would like to thank the following people for contributing to **Arduino CMake**
 .. _meadowstream: https://github.com/meadowstream
 .. _franramirez688: https://github.com/franramirez688
 .. _bshillingford: https://github.com/bshillingford
+.. _mikepurvis: https://github.com/mikepurvis
 
 License
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