Creating basic pkgdown generated documentation

[rmbielby]

I've added the yml scripting to create a pkgdown generated site on github.io.

This needed some fiddling around with how the donttest / dontrun flags are used as the way it was set up led to errors in rendering the code examples. Seemed like there were a few intermingled issues along the following lines:

• tidy_code() was scanning an intermediate example file (dfeshiny-Ex.R) when run by devools::checks(). That would fail depending on how \donttest and \dontrun were applied in the examples. I can't get to the intermediate file to see what tidy_code() was flagging, but there's a chance there's the output in there from other functions being run. Whatever it is, we don't have control over how dfeshiny-Ex.R is styled, so if it's created, it seems likely it will fail tidy_code() as an unintended consequence of running the checks (assuming I'm about understanding it right). I've added a \dontrun around tidy_code and that seems to be the key thing to prevent issues happening (note sure if I removed a \dontrun from it in the first place, will find out once I've seen the diff on this PR!).
• styler throws a parsing error when \dontrun and \donttest are added on subsequent lines to each other
• cookie_banner_server() needs \dontrun as it doesn't have access to the inputs it needs if run as an example
• cookie_banner_ui() and dfe_cookie_script both run fine as examples as inputs are either not needed or dummy variables can be given (so I've made sure \dontrun and \donttest aren't used around those)

Other than that, I've structured the reference in what I think is a sensible way and I've used the same (dark) theming as we use in the Analysts Guide (i.e. cyborg).

This covers items #26 and #33 in the Issues log.

[cjrace]

Doesn't seem like the favicon is set up / working correctly?

Can be a separate issue / PR though as it can get fiddly so not worth investing much time in before we get the main documentation live.

[rmbielby]

Yeah, wasn't sure if that was just not working with launching in preview or if it was properly not working. Agreed it's one to fix down the line.

[cjrace]

Raised #36 to come back to later

[cjrace]

Distinctly less jazzy than the rainbow you could have had...

In all seriousness it works well / looks good, aside from I think we need to add some custom CSS for the selected state in the navbar as it's pretty hard to read

[rmbielby]

Fixed. Gone for some nice blues!

[cjrace]

So you have - they work very nicely with the logo 👏

[cjrace]

Raised #36 to come back to later

[cjrace]

So you have - they work very nicely with the logo 👏