Add show command in order to show commit details

[joseluisq]

It would be great if we can support a command to show commit changes.

Proposal: I suggest to add a show command that performs git show --compact-summary HEAD by default which produces the following output in a compact way:

~> show
commit 10c403c9c7f7848d97d4896dc7fccb73daa5c6b0 (HEAD -> master, origin/master)
Author: Jose Quintana <jq@localhost>
Date:   Thu Feb 20 13:54:07 2020 +0100

    feat: some feature

 {src/lib => lib}/file.go                 |  0
 src/config/config.yml (new)              | 30 ++++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

Variants

# 1. Automatic: display the current commit (HEAD) by default
#    It performs: `git show --compact-summary HEAD`
~> show

# 2. Manual: it can support all `git show` flags as well
~> show --compact-summary HEAD~1