Doc updated

doc/UPGRADE_v9-v10.md

@@ -7,5 +7,7 @@ The main changes only concern:
 
 * new public methods added to the interfaces.
 * a new interface for the factory.
+* the parameters of the method `OTP::getQrCodeUri` are now required as the Google API is deprecated since April 2019. 
 
-The library now relies on the MBString extension. This extension is now a required dependency.
+The library now relies on the MBString extension.
+This extension is now a required dependency.

doc/index.md

@@ -18,8 +18,10 @@ Support for the version 9 will end when PHP 7.1 will not be maintained (1 Dec 20
 
 # Prerequisites
 
-This library needs at least `PHP 7.1`.
-It has been successfully tested using `PHP 7.1`, `PHP 7.2` and nightly branch.
+This library needs at least `PHP 7.1` for v9.0 and `PHP 7.2` for v10.0.
+It has been successfully tested using `PHP 7.1`, `PHP 7.2`, `PHP 7.3`.
+
+Nightly branch (`PHP 8.0`) fails as dependencies are not yet compatible.
 
 # Installation