Add beginner walkthrough documentation

docs/user/autocompletion.md

@@ -3,7 +3,7 @@
 One can generate autocompletion for its favorite shell using the following option:
 
 ```sh
-cargo run --release -- completion --generator <GENERATOR>
+cargo run -- completion --generator <GENERATOR>
 ```
 
 Where `GENERATOR` can be any of `bash`, `elvish`, `fish`, `powershell` and `zsh`.
@@ -14,7 +14,7 @@ First, get the completion file in a known place:
 
 ```sh
 mkdir -p ~/.local/share/duniter
-cargo run --release -- completion --generator bash > ~/.local/share/duniter/completion.bash
+cargo run -- completion --generator bash > ~/.local/share/duniter/completion.bash
 ```
 
 You can now manually source the file when needed:
@@ -30,3 +30,17 @@ Or you can automatically source it at `bash` startup by adding this to your `~/.
 ```
 
 You can now enjoy semantic completion of the `./target/release/duniter` command using `<Tab>` key.
+
+## Zsh
+
+Zsh equivalent
+
+```sh
+# make directory to store completion
+mkdir -p ~/.zsh/completion
+# write the completion script
+cargo run -- completion --generator zsh > ~/.zsh/completion/_duniter.zsh
+# add the following lines to your ~/.zshrc
+fpath+=(~/.zsh/completion)
+compinit # might slow down terminal startup
+```