Fix example

[avigoldman]

Currently, if you run the example you get the following error:

Potentially unhandled rejection [1] Error: Unrecognized node type: undefined
Node: "HELLO WORLD"

This is because you override the object { type: 'text', content: 'Hello world', location: ... } with the string HELLO WORLD.

This PR reassigns the content instead of overriding the object.

[coveralls]

Coverage remained the same at 100.0% when pulling 09ded00 on avigoldman:patch-1 into 5ec335b on reshape:master.

[jescalan]

Thanks for catching this and contributing the fix! 🙌