Update to installation documentation for M1 Macs

An update to the documentation here:

At the step where you update your path:

# If you're using Zsh
echo 'export PATH="/usr/local/opt/ruby/bin:/usr/local/lib/ruby/gems/3.0.0/bin:$PATH"' >> ~/.zshrc

On Apple M1 the path should be:

echo 'export PATH="/opt/homebrew/opt/ruby/bin:gem environment gemdir`/bin:$PATH"' >> ~/.zshrc

I found the paths here.

Are you missing a backtick there?

If you want to run shell command, backticks are outdated and this is the modern more flexible and clear syntax.

echo 'export PATH="/opt/homebrew/opt/ruby/bin:$(gem environment gemdir)/bin:$PATH"' >> ~/.zshrc

Also I would do it in two lines

GEM_PATH=$(gem environment gemdir)
export PATH="/opt/homebrew/opt/ruby/bin:$GEM_PATH/bin:$PATH"

Also you may be interested in this method that uses Ruby code to find the directory and should achieve the same effect

GEM_PATH="$(ruby -r rubygems -e 'puts Gem.dir')/bin"

If you install gems like this

gem install GEM --user-install 

Then use Gem.user_dir