[2.0.x] Fixed #28627 -- Added slug converter to some path() examples in docs.

Backport of 6da140724d from master

docs/ref/class-based-views/generic-display.txt

@@ -59,7 +59,7 @@ many projects they are typically the most commonly used views.
         from article.views import ArticleDetailView
 
         urlpatterns = [
-            path('<slug>/', ArticleDetailView.as_view(), name='article-detail'),
+            path('<slug:slug>/', ArticleDetailView.as_view(), name='article-detail'),
         ]
 
     **Example myapp/article_detail.html**:

docs/topics/http/urls.txt

@@ -80,7 +80,7 @@ Here's a sample URLconf::
         path('articles/2003/', views.special_case_2003),
         path('articles/<int:year>/', views.year_archive),
         path('articles/<int:year>/<int:month>/', views.month_archive),
-        path('articles/<int:year>/<int:month>/<slug>/', views.article_detail),
+        path('articles/<int:year>/<int:month>/<slug:slug>/', views.article_detail),
     ]
 
 Notes:
@@ -200,7 +200,7 @@ Here's the example URLconf from earlier, rewritten using regular expressions::
         path('articles/2003/', views.special_case_2003),
         re_path('articles/(?P<year>[0-9]{4})/', views.year_archive),
         re_path('articles/(?P<year>[0-9]{4})/(?P<month>[0-9]{2})/', views.month_archive),
-        re_path('articles/(?P<year>[0-9]{4})/(?P<month>[0-9]{2})/(?P<slug>[^/]+)/', views.article_detail),
+        re_path('articles/(?P<year>[0-9]{4})/(?P<month>[0-9]{2})/(?P<slug>[\w-_]+)/', views.article_detail),
     ]
 
 This accomplishes roughly the same thing as the previous example, except:

docs/topics/i18n/translation.txt

@@ -1315,8 +1315,8 @@ Example URL patterns::
 
     news_patterns = ([
         path('', news_views.index, name='index'),
-        path('category/<slug>/', news_views.category, name='category'),
-        path('<slug>/', news_views.details, name='detail'),
+        path('category/<slug:slug>/', news_views.category, name='category'),
+        path('<slug:slug>/', news_views.details, name='detail'),
     ], 'news')
 
     urlpatterns += i18n_patterns(
@@ -1385,8 +1385,8 @@ URL patterns can also be marked translatable using the
 
     news_patterns = ([
         path('', news_views.index, name='index'),
-        path(_('category/<slug>/'), news_views.category, name='category'),
-        path('<slug>/', news_views.details, name='detail'),
+        path(_('category/<slug:slug>/'), news_views.category, name='category'),
+        path('<slug:slug>/', news_views.details, name='detail'),
     ], 'news')
 
     urlpatterns += i18n_patterns(