Shows a warning and a confirmation prompt when running `ahoy init`
if an `.ahoy.yml` file already exists in the current directory and
would otherwise be overwritten.

BREAKING CHANGE: The warning prompt requires user input, so this may
require updating of e.g. scripted calls to `ahoy init`. The prompt
can be overruled by passing the "force" flag, e.g.
`ahoy init --force`

Also theoretically improve cross platform testing,
and replace deprecated `ioutil.*` functions as required.

Bring binary naming in Makefile in line with previous releases
(i.e. make a bare binary, named with suffixes, not in a tar.gz file).

Use Makefile foreach to reduce repetition.

Make ldflags more similar to Homebrew Go standard ldflags so
binaries downloaded from GH or built with Homebrew are more
closely aligned.

* docs: Update README

Fixed some typos, adjusted headings, cleaned up a little.

* Fix typo and add feature from docs

* Changed release download URL to always point to latest

Co-authored-by: Drew Robinson <drew.robinson@gaiaresources.com.au>

fix!: [#4] Show overwrite warning for `ahoy init`

…afterwards

chore: Realign binary naming & ldflags