Enterprise appendix

[ben]

This adds an appendix to cover GitHub Enterprise.

• Write the appendix

[ben]

Kind of wondering if this section is necessary. A summary is nice for a prose chapter, and as a transition to another one, but an Appendix doesn't really need any of that ceremony. I also notice that none of the other appendices have them. What do you think?

[xrd]

Let's ask Meghan. I think everything you wrote here sets the stage for enterprise. I think we should remove the pricing section; it is probably something that could change before the book is published and does not contribute to the "advanced" theme as much. Other than that, this is good stuff.

[ben]

OK, I reworded some things and made it a bit smoother. What do you think?

[xrd]

I think it would be interesting to discuss how different advanced tools work. For example, show how hub works with the enterprise server. Show an example of the ruby library configured to use the API from the enterprise server. And perhaps show how the network topology could be made more secure if services are all hosted inside the firewall. I'm not making a request for you to do all this, ben, just noting it as something for me to follow up on.

[ben]

Migrated the TODO into its own issue. I'm going to merge this for now, feel free to edit as you see fit.