Merge pull request #97 from ukgovdatascience/dependencies

Merge branch 'master' of https://github.com/ukgovdatascience/rap_companion into dependencies

Link to packrat issue, minor text changes

Lessen packrat focus, suggest other pkgs

Tidy and rearrange section 1.1

Improve containers section, other minor tidy-ups

Add 'minimise dependencies' section, correct spelling and grammar

Expand Docker section

Add Dcker links

Expand Packrat section of dependncy chapter

Expand dependency-management tool sections

Merge pull request #76 from ukgovdatascience/fix/75

Merge branch 'master' into fix/75

Add initial draft of dependency chapter (just Rmd)

Merge pull request #88 from ukgovdatascience/packrat