Fix for generating the filename of annex E

Signed-off-by: reinaortega <miguelangel.reinaortega@etsi.org>

src/example.py

@@ -56,7 +56,7 @@ def is_heading(txt :str):
     (Previously this predicate was used: ("Heading" in line.style.name) but 
     not all headings have the correct style
     '''
-    return txt.startswith("A.")
+    return (txt.startswith("A.")) or (txt.startswith("E."))
 
 def is_example_table(tab):
     return len(tab.rows) == 1 and len(tab.rows[0].cells) == 1