place deprecated warnings in calendars transform descriptions

Author: archmoj

src/components/calendars/index.js

@@ -234,12 +234,13 @@ module.exports = {
             }
         },
         transforms: {
-            description: 'This attribute is deprecated and it may be removed from the API in next major version.',
             filter: {
                 valuecalendar: makeAttrs([
+                    'WARNING: All transforms are deprecated and may be removed from the API in next major version.',
                     'Sets the calendar system to use for `value`, if it is a date.'
                 ].join(' ')),
                 targetcalendar: makeAttrs([
+                    'WARNING: All transforms are deprecated and may be removed from the API in next major version.',
                     'Sets the calendar system to use for `target`, if it is an',
                     'array of dates. If `target` is a string (eg *x*) we use the',
                     'corresponding trace attribute (eg `xcalendar`) if it exists,',