Few edits

Signed-off-by: Yogesh Deshpande <yogesh.deshpande@arm.com>

Author: yogeshbdeshpande

musings/psa-extension.md

@@ -63,13 +63,13 @@ UCCS-UAT = <TBD601>({
 
 * Cryptographic linkage of "utoken" with "pat"
 
-In order to cryptogrphically link "utoken" with "pat", the sequence to be followed is as under:
+In order to cryptographically link "utoken" with "pat", the sequence to be followed is as under:
 
 Upon receipt of "user data" from client application, 
 
 a. The binding layer initiates a Session with the "Attestation Verification Service" and receives 
 
-a "nonce" from the Service. The session intiation details can be found [here]
+a "nonce" from the Service. The session intiation details can be found [here](https://github.com/veraison/docs/tree/main/api/challenge-response#challengeresponse)
 
 b. The binding layer encodes a "utoken" as a CBOR data.