add how-to vignette for updating tech-doc

[sgaichas]

needed so that any of us can update this in coming years outline

• tech-doc is not like our other repos because it uses Travis-CI.

  • this means we don't pull, build locally, and push all to master.

  • instead we only edit rmd files and push those to master, letting Travis do the build.

• there is a need to check build status and diagnose errors on Travis (show how to do)

• major structural changes to repo folders change how books can be built and should be discussed prior to implementation, with documentation of changes

• other points to be discussed

[sgaichas]

we can implement how we published as a vingette as well; it is now in the chapters folder which isn't the best place

[kimberly-bastille]

Wiki outlining GitHub Actions use to build and deploy the book.