[Docs] Document newly added unitless css props in tips

tips/06-style-props-value-px.md

@@ -20,10 +20,17 @@ See [Inline Styles](/react/tips/inline-styles.html) for more info.
 
 Sometimes you _do_ want to keep the CSS properties unitless. Here's a list of properties that won't get the automatic "px" suffix:
 
+- `columnCount`
 - `fillOpacity`
+- `flex`
+- `flexGrow`
+- `flexShrink`
 - `fontWeight`
+- `lineClamp`
 - `lineHeight`
 - `opacity`
+- `order`
 - `orphans`
+- `widows`
 - `zIndex`
 - `zoom`