docs: fix typo in README

README.md

@@ -88,7 +88,7 @@ IMPORTANT WARNINGS
 
 Though **NFS4J** is used by the [dCache](https://dcache.org) and other projects in production,
 the public API is still _unstable_ and subject to change (indicated by leading zero in the
-version number). Thus, is should be considered as `beta`.
+version number). Thus, should be considered as `beta`.
 
 Please consult the [API changes](API-changes.md) document when switching between version numbers.
 The patch level releases are not affected by API changes, of course.