[1.7.x] Fixed #23558 -- documented slugify limitations

Backport of 03467368db from master

django/template/defaultfilters.py

@@ -232,9 +232,9 @@ def make_list(value):
 @stringfilter
 def slugify(value):
     """
-    Converts to lowercase, removes non-word characters (alphanumerics and
-    underscores) and converts spaces to hyphens. Also strips leading and
-    trailing whitespace.
+    Converts to ASCII. Converts spaces to hyphens. Removes characters that
+    aren't alphanumerics, underscores, or hyphens. Converts to lowercase.
+    Also strips leading and trailing whitespace.
     """
     return _slugify(value)
 

django/utils/text.py

@@ -435,9 +435,9 @@ unescape_string_literal = allow_lazy(unescape_string_literal)
 
 def slugify(value):
     """
-    Converts to lowercase, removes non-word characters (alphanumerics and
-    underscores) and converts spaces to hyphens. Also strips leading and
-    trailing whitespace.
+    Converts to ASCII. Converts spaces to hyphens. Removes characters that
+    aren't alphanumerics, underscores, or hyphens. Converts to lowercase.
+    Also strips leading and trailing whitespace.
     """
     value = unicodedata.normalize('NFKD', value).encode('ascii', 'ignore').decode('ascii')
     value = re.sub('[^\w\s-]', '', value).strip().lower()

docs/ref/templates/builtins.txt

@@ -2036,9 +2036,9 @@ If ``some_list`` is ``['a', 'b', 'c']``, the output will be ``['a', 'b']``.
 slugify
 ^^^^^^^
 
-Converts to lowercase, removes non-word characters (alphanumerics and
-underscores) and converts spaces to hyphens. Also strips leading and trailing
-whitespace.
+Converts to ASCII. Converts spaces to hyphens. Removes characters that aren't
+alphanumerics, underscores, or hyphens. Converts to lowercase. Also strips
+leading and trailing whitespace.
 
 For example::
 

docs/ref/utils.txt

@@ -817,9 +817,9 @@ appropriate entities.
 
 .. function:: slugify
 
-    Converts to lowercase, removes non-word characters (alphanumerics and
-    underscores) and converts spaces to hyphens. Also strips leading and
-    trailing whitespace.
+    Converts to ASCII. Converts spaces to hyphens. Removes characters that
+    aren't alphanumerics, underscores, or hyphens. Converts to lowercase. Also
+    strips leading and trailing whitespace.
 
     For example::