Fix descriptions for shapes.layer and newshape.layer

Author: my-tien

src/components/shapes/attributes.js

@@ -116,7 +116,7 @@ module.exports = templatedArray('shape', {
         description: [
             'Specifies whether shapes are drawn below gridlines (*below*),',
             'between gridlines and traces (*between*) or above traces (*above*).'
-        ]
+        ].join(' ')
     },
 
     xref: extendFlat({}, annAttrs.xref, {

src/components/shapes/draw_newshape/attributes.js

@@ -122,7 +122,7 @@ module.exports = overrideAll({
             description: [
                 'Specifies whether new shapes are drawn below gridlines (*below*),',
                 'between gridlines and traces (*between*) or above traces (*above*).'
-            ]
+            ].join(' ')
         },
         drawdirection: {
             valType: 'enumerated',

test/plot-schema.json

@@ -3720,10 +3720,7 @@
      }
     },
     "layer": {
-     "description": [
-      "Specifies whether new shapes are drawn below gridlines (*below*),",
-      "between gridlines and traces (*between*) or above traces (*above*)."
-     ],
+     "description": "Specifies whether new shapes are drawn below gridlines (*below*), between gridlines and traces (*between*) or above traces (*above*).",
      "dflt": "above",
      "editType": "none",
      "valType": "enumerated",
@@ -7712,10 +7709,7 @@
        }
       },
       "layer": {
-       "description": [
-        "Specifies whether shapes are drawn below gridlines (*below*),",
-        "between gridlines and traces (*between*) or above traces (*above*)."
-       ],
+       "description": "Specifies whether shapes are drawn below gridlines (*below*), between gridlines and traces (*between*) or above traces (*above*).",
        "dflt": "above",
        "editType": "arraydraw",
        "valType": "enumerated",