Fix braces in tutorial 😭

In #1172 I tried to update
these docs to use the new brace syntax but I only half updated this
example :( And we have no tests for examples embedded in our docs so we
can't catch this.

Thanks for the bug report @moficodes !!!

docs/tutorial.md

@@ -190,9 +190,9 @@ spec:
       command:
         - /kaniko/executor
       args:
-        - --dockerfile=$(inputs.params.pathToDockerFile}
-        - --destination=$(outputs.resources.builtImage.url}
-        - --context=$(inputs.params.pathToContext}
+        - --dockerfile=$(inputs.params.pathToDockerFile)
+        - --destination=$(outputs.resources.builtImage.url)
+        - --context=$(inputs.params.pathToContext)
 ```
 
 `TaskRun` binds the inputs and outputs to already defined `PipelineResources`,