update docs

README.md

@@ -74,7 +74,7 @@ _Note: `ng build --configuration production` does not currently work for ATT&CK
 
 ## Documentation
 
-When viewing the app in a browser, click on the **?** icon to the right of the **ATT&CK® Navigator** title to view its documentation.
+When viewing the Navigator in a browser, click on the **?** icon in the upper right corner to view the in-app documentation.
 
 ## Layers Folder
 
@@ -238,6 +238,10 @@ The following is an example iframe which embeds our [*Bear APTs](layers/data/sam
 
 [Cyber Threat Intelligence repository](https://github.com/mitre/cti) of the ATT&CK catalog expressed in STIX 2.0 JSON.
 
+### ATT&CK STIX Data
+
+[ATT&CK STIX Data repository](https://github.com/mitre-attack/attack-stix-data) of the ATT&CK catalog expressed in STIX 2.1 JSON.
+
 ### ATT&CK
 
 ATT&CK® is a curated knowledge base and model for cyber adversary behavior, reflecting the various phases of an adversary’s lifecycle and the platforms they are known to target. ATT&CK is useful for understanding security risk against known adversary behavior, for planning security improvements, and verifying defenses work as expected.