Update CppCoreGuidelines.md

Author: AndrewPardoe

CppCoreGuidelines.md

@@ -16251,11 +16251,11 @@ and should be used only as building blocks for meaningful concepts, rather than
 
     int x = 7;
     int y = 9;
-    auto z = plus(x, y);   // z = 16
+    auto z = algo(x, y);   // z = 16
 
     string xx = "7";
     string yy = "9";
-    auto zz = plus(xx, yy);   // zz = "79"
+    auto zz = algo(xx, yy);   // zz = "79"
 
 Maybe the concatenation was expected. More likely, it was an accident. Defining minus equivalently would give dramatically different sets of accepted types.
 This `Addable` violates the mathematical rule that addition is supposed to be commutative: `a+b == b+a`.