add docs

Author: leoromanovsky

packages/flagging/README.md

@@ -1,3 +1,27 @@
 # Flagging SDK
 
 This package supports flagging and experimentation by performing evaluation in the browser.
+
+## Initialize
+
+```
+const datadogFlaggingProvider = createDatadogProvider()
+
+// provide the subject
+const subject = {
+  key: 'subject-key-1',
+}
+await OpenFeature.setContext(subject)
+
+// initialize
+await OpenFeature.setProviderAndWait(datadogFlaggingProvider)
+```
+
+## Evaluation
+
+```
+const client = OpenFeature.getClient()
+
+// provide the flag key and a default value which is returned for exceptional conditions.
+const flagEval = client.getBooleanValue('<FLAG_KEY>', false)
+```