zsh type completion install docs don't account for homebrew destinations

References in the docs for type completion linking for zsh point at /opt/kubectx which doesn't appear for homebrew installation. The type completion is in /opt/homebrew/opt/kubectx/share/zsh/site_functions. If there are variances in where these land, it would perhaps be prudent to expand the docs to indicate the differences.

For reference: https://github.com/ahmetb/kubectx?tab=readme-ov-file#completion-scripts-for-plain-zsh