docs: add doc for elemental button component

hperrin · hperrin · commit 1764c2abb788 · 2020-01-30T16:20:10.000-08:00
diff --git a/packages/common/README.md b/packages/common/README.md
@@ -67,6 +67,10 @@ An elemental component for the `a` tag.
 
 An elemental component for the `aside` tag.
 
+## Button.svelte
+
+An elemental component for the `button` tag.
+
 ## Div.svelte
 
 An elemental component for the `div` tag.
