Update documentation

[gcharest]

Need to update project documentation to explain how one can easily modify theme to different one than Canada.

[CalvinRodo]

Unfortunately at the moment the CDTS documentation resides on GC Code the new version is being open sourced but I'm not sure the existing version has been opened yet.

https://gitlab.com/esdc-edsc/next_centrally_deployed_templates_solution

Ideally we can just point them to that, although if we truly want this to be extensible we should probably decouple from CDTS since I'm not sure it's meant for use by those outside of GoC or we are able to override the theme that way.

Shouldn't be terribly difficult we'd just have to copy the WET files down might also simplify solving issue #39

Once again I'll reach out to @shawnthompson about this.

[shawnthompson]

Hello again!

CDTS is themed only for GoC sites / applications. We have no intention on decoupling it from GCWeb / GCIntranet.

Although the new CDTS (no date confirmed for beta) is going to be opened source, you will be able to modify it and use it in your own them themes. Although we will only be supporting the GoC themes we create. It's in the early stages of planning now, stay tuned.