Add block documentation

docs/_data/variables/form/shared.json

@@ -1,5 +1,12 @@
 {
   "by_name": {
+    "$form-colors": {
+      "name": "$form-colors",
+      "value": "$colors",
+      "type": "variable",
+      "computed_type": "function",
+      "computed_value": "mergeColorMaps((\"white\": ($white, $black), \"black\": ($black, $white), \"light\": ($light, $light-invert), \"dark\": ($dark, $dark-invert), \"primary\": ($primary, $primary-invert, $primary-light, $primary-dark), \"link\": ($link, $link-invert, $link-light, $link-dark), \"info\": ($info, $info-invert, $info-light, $info-dark), \"success\": ($success, $success-invert, $success-light, $success-dark), \"warning\": ($warning, $warning-invert, $warning-light, $warning-dark), \"danger\": ($danger, $danger-invert, $danger-light, $danger-dark)), $custom-colors)"
+    },
     "$input-color": {
       "name": "$input-color",
       "value": "$text-strong",
@@ -130,6 +137,7 @@
     }
   },
   "list": [
+    "$form-colors",
     "$input-color",
     "$input-background-color",
     "$input-border-color",