Enabling misspell and goimports in golangci-lint allows a bit of
simplification of tools.go / Makefile.
The linters enabled locally also complained about the markdown in
README.md a little, so I fixed those complaints.
I also enabled auto-fix mode in golangci-lint so that it will just
fix any lint issues it runs across (which is how goimports/misspell)
was being used.
misspell still needs to be included in tools.go unless we decide that
we didn't want it to run on markdown files.
