Mention file target locations in the README

It would be helpful to mention where the files from the release archive are meant to go, even if just as example.

```
/usr/local/bin/dysk
/usr/local/share/man/man1/dysk.1
/usr/local/share/bash-completion/completions/_dysk
/usr/local/share/bash-completion/completions/dysk.bash
/usr/local/share/bash-completion/completions/dysk.elv
/usr/local/share/bash-completion/completions/dysk.fish
```
are the places for my install, the man and bash-completion paths were not immediately obvious.

Open the README and find the section describing installation from the release archive. Document the example destinations for the dysk binary, man page, and shell-completion files listed in the issue; the README is done when these target paths are clear to someone installing the release.

Written by the indexing model from the issue text.