Mention in description that drawminorticklabel only applies to period axes

Author: my-tien

src/plots/cartesian/layout_attributes.js

@@ -703,6 +703,7 @@ module.exports = {
         valType: 'integer',
         editType: 'calc',
         description: [
+            'Only for date axes with `ticklabelmode` *period*.',
             'Instead of drawing the major tick label, draw the label for the minor tick',
             'that is n positions away from the major tick. E.g. to always draw the label for the',
             'minor tick before each major tick, choose `drawminorticklabel` -1'

test/plot-schema.json

@@ -14098,7 +14098,7 @@
      "valType": "info_array"
     },
     "drawminorticklabel": {
-     "description": "Instead of drawing the major tick label, draw the label for the minor tick that is n positions away from the major tick. E.g. to always draw the label for the minor tick before each major tick, choose `drawminorticklabel` -1",
+     "description": "Only for date axes with `ticklabelmode` *period*. Instead of drawing the major tick label, draw the label for the minor tick that is n positions away from the major tick. E.g. to always draw the label for the minor tick before each major tick, choose `drawminorticklabel` -1",
      "editType": "calc",
      "valType": "integer"
     },
@@ -15729,7 +15729,7 @@
      "valType": "info_array"
     },
     "drawminorticklabel": {
-     "description": "Instead of drawing the major tick label, draw the label for the minor tick that is n positions away from the major tick. E.g. to always draw the label for the minor tick before each major tick, choose `drawminorticklabel` -1",
+     "description": "Only for date axes with `ticklabelmode` *period*. Instead of drawing the major tick label, draw the label for the minor tick that is n positions away from the major tick. E.g. to always draw the label for the minor tick before each major tick, choose `drawminorticklabel` -1",
      "editType": "calc",
      "valType": "integer"
     },