[temp] Add L suffix to literal value example definition of constexpr

variable template 'pi', to address questions about whether it would
do the right thing for 'long double'.

Author: zygoloid

source/templates.tex

@@ -63,7 +63,7 @@
 \enterexample
 \begin{codeblock}
 template<class T>
-  constexpr T pi = T(3.1415926535897932385);
+  constexpr T pi = T(3.1415926535897932385L);
 template<class T>
 T circular_area(T r) {
   return pi<T> * r * r;