docs($interpolate): demonstrate a filter in the interpolated expression

Closes #5186

Author: esgy

src/ng/interpolate.js

@@ -103,8 +103,8 @@ function $InterpolateProvider() {
      *
        <pre>
          var $interpolate = ...; // injected
-         var exp = $interpolate('Hello {{name}}!');
-         expect(exp({name:'Angular'}).toEqual('Hello Angular!');
+         var exp = $interpolate('Hello {{name | uppercase}}!');
+         expect(exp({name:'Angular'}).toEqual('Hello ANGULAR!');
        </pre>
      *
      *