Add docs for command completion (#410)

docs/command_completion.md

@@ -0,0 +1,53 @@
+# Command Completion 
+
+MVT utilizes the [Click](https://click.palletsprojects.com/en/stable/) library for creating its command line interface. 
+
+Click provides tab completion support for Bash (version 4.4 and up), Zsh, and Fish.
+
+To enable it, you need to register a special function with your shell, which varies depending on the shell you are using.
+
+`You need to start a new shell in order for the changes to be loaded.`
+
+### For Bash
+
+```bash
+# Get the completion scripts 
+curl --tlsv1.3 -O https://github.com/mvt-project/mvt/tree/main/src/mvt/shell_completion/.mvt-{ios,android}-complete.bash
+
+# Source the file in ~/.bashrc.
+. .mvt-android-complete.bash && . .mvt-ios-complete.bash
+```
+
+### For Zsh
+
+```bash
+# Get the completion scripts 
+curl --tlsv1.3 -O https://github.com/mvt-project/mvt/tree/main/src/mvt/shell_completion/.mvt-{ios,android}-complete.zsh
+
+# Source the file in ~/.zshrc.
+. .mvt-android-complete.zsh && . .mvt-ios-complete.zsh
+```
+
+## Generate Scripts locally 
+
+In case you prefer not to download the command completion scripts from the MVT Project, you can generate your own scripts locally.
+
+### For Bash
+
+```bash
+echo "$(_MVT_IOS_COMPLETE=bash_source mvt-ios)" > ~/.mvt-ios-complete.bash &&
+echo "$(_MVT_ANDROID_COMPLETE=bash_source mvt-android)" > ~/.mvt-android-complete.bash
+```
+
+### For Zsh
+```bash
+echo "$(_MVT_IOS_COMPLETE=zsh_source mvt-ios)" >  ~/.mvt-ios-complete.zsh &&
+echo "$(_MVT_ANDROID_COMPLETE=zsh_source mvt-android)" > ~/.mvt-android-complete.zsh
+```
+
+You will then need to source the files in your shell configuration file and restart it for the changes to be loaded.
+
+
+For more information, visit the official [Click Docs](https://click.palletsprojects.com/en/stable/shell-completion/#enabling-completion).
+
+