Document number input functionality (#1610)

docs/pages/docs/fixtures/ui-controls.mdx

@@ -25,7 +25,13 @@ export default () => {
 
 The `useValue` hook can be used to control any type of serializable data, like strings, numbers and booleans, including objects and arrays.
 
-> The [Boolean Input Plugin](/docs/plugins#boolean-input-plugin) can be installed to turn boolean controls into checkboxes.
+### Number inputs
+
+While focused on number inputs you can use the up and down arrow keys to increment and decrement the value. Hold ⎇ for .1 increments, ⇧ for 10 increments, and ⌘ for 100 increments.
+
+### Boolean inputs
+
+The [Boolean Input Plugin](/docs/plugins#boolean-input-plugin) can be installed to turn boolean controls into checkboxes.
 
 ## `useSelect`