improve description

Author: archmoj

src/plots/cartesian/layout_attributes.js

@@ -422,7 +422,8 @@ module.exports = {
             'A value of 1 (default) means each tick gets a label.',
             'A value of 2 means shows every 2nd level.',
             'A larger value n means only every nth tick is labeled.',
-            '`tick0` determines which labels are shown.'
+            '`tick0` determines which labels are shown.',
+            'Not implemented for an axis with `type` of *log* or *multicategory*.'
         ].join(' ')
     },
     tickvals: {