Tutorial generics typos (#175)

Just two small typo fixes.

Author: cneumann

docs/understanding-generics.md

@@ -298,14 +298,14 @@ Benefits of Slang's approach:
   what methods are valid for generic types, unlike C++ template parameters.
 
 There are certain things which work with C++ style templates, which are
-(deliberatly) disallowed with Slang generics. For example the following code
+(deliberately) disallowed with Slang generics. For example the following code
 will work in C++ but the naïve equivalent in Slang will not compile.
 
 ```cpp
 // This function will compile when instantiated at a type which supports the +
 // operator. However this restriction is only discovered at the call site.
-template<T>
-float addValue(T v0, T v1) { return v0.x + v1.x; }
+template<typename T>
+float addValue(T v0, T v1) { return v0 + v1; }
 
 // We happen to call `addValue` with a type that supports addition.
 void user() {addValue(1,2); }