Update command line completion docs (#793)

* update command line completion docs

* add brew command line completion sub-section in installation docs

docs/command-line-completion.md

@@ -12,9 +12,9 @@ By default this command will print on the standard output (the shell window) the
 Use `arduino-cli completion bash > arduino-cli.sh` to generate the completion file.
 At this point you can move that file in `/etc/bash_completion.d/` (root access is required) with `sudo mv arduino-cli.sh /etc/bash_completion.d/`.
 
-A not recommended alternative is to source the completion file in `.bashrc`.
+A not recommended alternative is to source the completion file in `~/.bashrc`.
 
-Remember to open a new shell to test the functionality
+Remember to open a new shell to test the functionality.
 
 ### Zsh
 Use `arduino-cli completion zsh > _arduino-cli` to generate the completion file.
@@ -23,23 +23,23 @@ At this point you can place the file in a directory listed in your `fpath` if yo
 Or if you want you can create a directory, add it to your `fpath` and copy the file in it:
 
 1. `mkdir ~/completion_zsh`
-2. add `fpath=($HOME/completion_zsh $fpath)` at the beginning of your `.zshrc` file
+2. add `fpath=($HOME/completion_zsh $fpath)` at the beginning of your `~/.zshrc` file
 3. `mv _arduino-cli ~/completion_zsh/`
 
-Remember to open a new shell to test the functionality
-
-*N.B.*
-The Zsh completion is working with [Oh-My-Zsh](https://ohmyz.sh/) but not with [Prezto](https://github.com/sorin-ionescu/prezto) (the zsh completion system is working in a different way than classic zsh). But hopefully it will be fixed in the future
+Remember to open a new shell to test the functionality.
 
 ### Fish
 Use `arduino-cli completion fish > arduino-cli.fish` to generate the completion file.
 At this point you can place the file in `~/.config/fish/completions` as stated in the [official documentation](http://fishshell.com/docs/current/index.html#where-to-put-completions).
 Remember to create the directory if it's not already there `mkdir -p ~/.config/fish/completions/` and then place the completion file in there with `mv arduino-cli.fish ~/.config/fish/completions/`
 
-Remember to open a new shell to test the functionality
+Remember to open a new shell to test the functionality.
 
 #### Disabling command and flag descriptions
 By default fish completion has command and flag description enabled by default. If you want to disable this behaviour you can simply pass the `--no-descriptions` flag when calling `completion` command and the generated file will not have descriptions
 
 *N.B.*
 This flag is not compatible with bash or zsh
+
+### Brew
+If you install the `arduino-cli` using [homebrew](https://brew.sh/) package manager the completion should work out of the box if you have followed the [official documentation](https://docs.brew.sh/Shell-Completion).

docs/installation.md

@@ -7,6 +7,8 @@ The Arduino CLI is available as a Homebrew formula since version
 brew update
 brew install arduino-cli
 ```
+#### Command line completion
+[Command line completion](command-line-completion.md#brew) files are already bundled in the homebrew installation.
 
 ### Use the install script