Update go.mod to use go v1.15 (#146)

diff --git a/README.md b/README.md
index 92a53e1..3254655 100644
--- a/README.md
+++ b/README.md
@@ -67,7 +67,7 @@
 $ go build -v ./whisk
 ```
 
-> **Note**: There is no `main` function in this project as the `./whish` packages are treated together as a client library.
+> **Note**: There is no `main` function in this project as the `./whisk` packages are treated together as a client library.
 
 ### Testing using `go test`
 
diff --git a/go.mod b/go.mod
index 867db3c..0491f2d 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/apache/openwhisk-client-go
 
-go 1.14
+go 1.15
 
 require (
 	github.com/BurntSushi/toml v0.3.1 // indirect