Docs: document isDefault option for block styles (#10207)

Documents `isDefault` option when adding block style variations with `wp.blocks.registerBlockStyle()` [Example](https://github.com/WordPress/gutenberg/blob/3b6c167cab50e77c44b21c74e3dd2bdf8b890ff4/packages/block-library/src/separator/index.js#L20-L24).
WordPress · Oct 8, 2018 · 377c222 · 377c222
1 parent 9d419fa
commit 377c222
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/docs/extensibility/extending-blocks.md b/docs/extensibility/extending-blocks.md
@@ -21,6 +21,8 @@ wp.blocks.registerBlockStyle( 'core/quote', {
 
 The example above registers a block style variation named `fancy-quote` to the `core/quote` block. When the user selects this block style variation from the styles selector, an `is-style-fancy-quote` className will be added to the block's wrapper.
 
+By adding `isDefault: true`, you can make registered style variation to be active by default when a block is inserted.
+
 ### Filters
 
 Extending blocks can involve more than just providing alternative styles, in this case, you can use one of the following filters to extend the block settings.