Changed the e^v clarification in source

Earlier I made the change in the html generated by doxygen rather than the source used to generate the documentation.

glm/exponential.hpp

@@ -35,7 +35,7 @@ namespace glm
  template<length_t L, typename T, qualifier Q>
  GLM_FUNC_DECL vec<L, T, Q> pow(vec<L, T, Q> const& base, vec<L, T, Q> const& exponent);
 
- /// Returns the natural exponentiation of x, i.e., e^x.
+ /// Returns the natural exponentiation of v, i.e., e^v.
  ///
  /// @param v exp function is defined for input values of v defined in the range (inf-, inf+) in the limit of the type qualifier.
  /// @tparam L An integer between 1 and 4 included that qualify the dimension of the vector.