Certificate chain articles

Here's a list of articles we need to provide

- [x] What is an certificate chain?
- [ ] What is an Root certificate?
- [ ] What is an intermediate certificate?
- [ ] Root & Intermediate Certificate Bundles
- [ ] Difference between Root Certificate, Intermediate Certificate and SSL Certificate

We also need to include some specific detail about creating the appropriate Comodo bundle (#31).
The sentence beginning "Certificate 6," is somewhat confusing since the root certificate is at the end of the list, but mentioned as the top of the chain. Perhaps that could use a little more explanation.