add zsh autocomplete

docs/user/autocompletion.md

@@ -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 --release -- completion --generator zsh > ~/.zsh/completion/_duniter.zsh
+# add the following lines to your ~/.zshrc
+fpath+=(~/.zsh/completion)
+compinit # might slow down terminal startup
+```