Fix typo

Co-authored-by: Owen Mansel-Chan <62447351+owen-mc@users.noreply.github.com>

docs/codeql/codeql-language-guides/customizing-library-models-for-go.rst

@@ -158,7 +158,7 @@ This pattern covers many of the cases where we need to summarize flow through a
     func TaintFlow() {
         elems := []string{"Hello", "World"}
         sep := " "
-        t := strings.Join(elems, sep) // There is taint flow from ss and sep to t.
+        t := strings.Join(elems, sep) // There is taint flow from elems and sep to t.
         ...
     }