Don't output help on helm plugin install

[z0rc]

I'm installing helm-diff as part of CI pipeline. Every time plugin installation outputs help page.

I found this unwelcome, as in CI pipeline context this output is effectively a noise. Also it isn't possible to properly silence it. I can do helm plugin install ... >/dev/null, but this will also omit output from helm itself, which is actually valuable.

[yxxhero]

PR is welcome

[z0rc]

@yxxhero I can just remove https://github.com/databus23/helm-diff/blob/master/install-binary.sh#L146-L152 and https://github.com/databus23/helm-diff/blob/master/install-binary.sh#L166, right? Or do you expect something else?

[yxxhero]

@mumoshu @databus23 WDYT?

[yxxhero]

@z0rc PR is welcome.