Add additional test for safe case in documentation

Author: joefarebrother

python/ql/test/library-tests/frameworks/jinja2/template_test.py

@@ -1,7 +1,11 @@
 from jinja2 import Environment, Template
+from jinja2.sandbox import SandboxedEnvironment
 
 def test():
     env = Environment()
     t = env.from_string("abc") # $ templateConstruction="abc"
     t = Template("abc") # $ templateConstruction="abc"
+
+    env2 = SandboxedEnvironment()
+    t = env.from_string("abc") # No result as we don't model SandboxedEnvironment. We may wish to instead specifically model it as NOT vulnerable to template injection vulnerabilities.
     return t