Update status in README (#15)

Resolves #14
diff --git a/README.md b/README.md
index f8992a2..065088f 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@
 
 ## Status
 
-Beta
+Stable: No breaking changes will be made before 2.0.
 
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