Add missing detail to Updating the Kit Documentation

[paulmsmith]

Adds additional step to the documentation for users to run npm install as a first pass at fixing any post updating errors.

Think this is worth having in? @joelanman @gemmaleigh if so, can it be proof read. :)

[gemmaleigh]

I think it would be good if this is consistent with the instructions already in the docs:

install/install-the-kit.md
install/run-the-kit.md

In terminal:

npm start

After the kit has started, you should see a message telling you that the kit is running:

Listening on port 3000 url: http://localhost:3000

If you see an error after updating, you may need to download extra code used by the kit before it can run.

You can get this by running:

npm install

The install may take up to a minute. Whilst installing it may WARN about some items - this is ok. As long as there are no ERRORs you can continue.

In terminal:

npm start

After the kit has started, you should see a message telling you that the kit is running:

Listening on port 3000 url: http://localhost:3000

If you still have an error, you can raise an issue within github or ask in the Slack channel for users of the prototype kit.

Try to provide as much information as you can about the error and the computer you are attempting to run the prototyping kit on.

[gemmaleigh]

cc. @edwardhorsford as I'm copy-and-pasting your docs here.

[paulmsmith]

Better to repeat that in context with the upgrade docs or link to it from the documentation I've written?

[joelanman]

I don't think its easy to link to this content as it stands, so yeh just copying and pasting for consistency would be good.

I don't think we need the second instance of:

After the kit has started, you should see a message telling you that the kit is running:

Listening on port 3000 url: http://localhost:3000

as we've just said that above

[gemmaleigh]

Hi @paulmsmith I've copied these changes over to #316.