Remove trailing slash

Author: databus23

README.md

@@ -25,7 +25,7 @@ $ helm diff [flags] RELEASE CHART
 ### Using Helm plugin manager (> 2.3.x)
 
 ```shell
-helm plugin install https://github.com/databus23/helm-diff/
+helm plugin install https://github.com/databus23/helm-diff
 ```
 
 ### Pre Helm 2.3.0 Installation