Typo fixed in: Update README.md (#1685)

Hi, 

There is a typo in this text.

"This directroy contains integration tests" – should be "This directory
contains integration tests".

Thanks.

Signed-off-by: 0xbasar <109233435+0xbasar@users.noreply.github.com>

Author: 0xbasar

integration/subxt-tests/README.md

@@ -1,6 +1,6 @@
 # Solang `subxt` integration test suite
 
-This directroy contains integration tests against a real node using `subxt`.
+This directory contains integration tests against a real node using `subxt`.
 
 ## How to execute the tests