restoring wiki_markup where still used

core/templatetags/wiki_markup.py

@@ -7,6 +7,12 @@ from troggle.core.models_caves import LogbookEntry, QM, Cave
 import re, urllib.parse
 
 register = template.Library()
+'''Several templates are still (2021) using these wiki filters extensively to process data extracted from the database,
+and to restructure values into valid URLs to go elsewhere in the system, even where these are not actually 'wiki'. See
+the regexes at the end of this file.
+So the data in the database needs to be checked that there is no wiki-format content before these are deleted, and the
+filter functions of these regexes needs to be explored in practice.
+'''
 
 @register.filter()
 def plusone(n):