Fix markdown rendering on some pages, and add a link to the syntax help

Signed-off-by: Skia <skia@libskia.so>

sith/settings.py

@@ -318,6 +318,9 @@ SITH_CLUB_REFOUND_ID = 89
 SITH_COUNTER_REFOUND_ID = 38
 SITH_PRODUCT_REFOUND_ID = 5
 
+# Pages
+SITH_CORE_PAGE_SYNTAX = "Aide_sur_la_syntaxe"
+
 # Forum
 
 SITH_FORUM_PAGE_LENGTH = 30