fix typos

Author: Rotzbua

.github/CONTRIBUTING.md

@@ -1,10 +1,8 @@
 Code style
 ----------
 
-1. Please use ``fixed integers``, see `stdint.h`_. Why? This library is compatible to different boards which use different architectures (16bit vs 32bit). So unfixed ``int`` has different sizes on different environments and may cause unpredictable behaviour.
+1. Please use `fixed integers`, see `stdint.h`_. Why? This library is compatible to different boards which use different architectures (8bit vs 32bit). So unfixed `int` has different sizes on different environments and may cause unpredictable behaviour.
 
 2. If possible: use advantages of `c++11`, e.g. `constexpr`.
 
-3. Use tab in source files. Space in examples.
-
-4. Add documentation to **every** new function or parameter. Add documentation to most steps in your source code.
+3. Add documentation to **every** new function or parameter. Add documentation to most steps in your source code.