Fixed server examples (#1437)

server9.py was modified to use the strong tag at #963,
but the others were not.

Author: bunhere

src/server10.py

@@ -99,7 +99,7 @@ def show_comments(session):
         out += "<i>by " + html.escape(who) + "</i></p>"
 
     out += "<link rel=stylesheet src=/comment.css>"
-    out += "<label></label>"
+    out += "<strong></strong>"
     out += "<script src=/comment.js></script>"
     out += "<script src=https://example.com/evil.js></script>"
     return out

src/server12.py

@@ -124,7 +124,7 @@ def show_comments(session):
         out += "<i>by " + html.escape(who) + "</i></p>"
 
     out += "<link rel=stylesheet src=/comment.css>"
-    out += "<label></label>"
+    out += "<strong></strong>"
     out += "<script src=/comment.js></script>"
     out += "<script src=https://example.com/evil.js></script>"
     return out