adding description of forceHTTPS key in oauth2 middleware (#1142)

Co-authored-by: Yaron Schneider <yaronsc@microsoft.com>

daprdocs/content/en/operations/security/oauth.md

@@ -71,6 +71,12 @@ spec:
     value: "<redirect URL>"
   - name: authHeaderName
     value: "<header name under which the secret token is saved>"
+    # forceHTTPS:
+    # This key is used to set HTTPS schema on redirect to your API method 
+    # after Dapr successfully received Access Token from Identity Provider. 
+    # By default, Dapr will use HTTP on this redirect.
+  - name: forceHTTPS
+    value: "<set to true if you invoke an API method through Dapr from https origin>"
 ```
 
 ### Define a custom pipeline for an Authorization Code Grant