Merge pull request #174 from JoshVanL/istio-csr-support-istio-1.10+

Update README.md to state that istio-csr only now supports istio v1.10+

Author: jetstack-bot

README.md

@@ -23,7 +23,7 @@ Certificates facilitating mTLS — both inter
 and intra-cluster — will be signed, delivered and renewed using [cert-manager
 issuers](https://cert-manager.io/docs/concepts/issuer).
 
-istio-csr supports Istio v1.7+ and cert-manager v1.3+
+istio-csr supports Istio v1.10+ and cert-manager v1.3+
 
 ---