docs: elaborate on how style auto-prefixing works (#1062)

src/guide/class-and-style.md

@@ -230,7 +230,7 @@ The array syntax for `:style` allows you to apply multiple style objects to the
 
 ### Auto-prefixing
 
-When you use a CSS property that requires [vendor prefixes](https://developer.mozilla.org/en-US/docs/Glossary/Vendor_Prefix) in `:style`, for example `transform`, Vue will automatically detect and add appropriate prefixes to the applied styles.
+When you use a CSS property that requires a [vendor prefix](https://developer.mozilla.org/en-US/docs/Glossary/Vendor_Prefix) in `:style`, Vue will automatically add the appropriate prefix. Vue does this by checking at runtime to see which style properties are supported in the current browser. If the browser doesn't support a particular property then various prefixed variants will be tested to try to find one that is supported.
 
 ### Multiple Values