docs for cli

cli/docs/internal/commands.md

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+# Cli Internal Docs
+
+## Repl Custom Commands Arg Parser 
+
+To distinguish between normal SQL queries and custom commands, we prefix a "." before our desired command. This signals to the to the REPL that you intend to use a custom command. 
+
+To implement this we use CLAP with multicall. It is very important we use multicall, else this will not work
+
+## Adding new Commands
+
+To add new commands, we need to modify three places: 
+- `commands/mod.rs` 
+- `commands/args.rs` or create a new file under `commands` that will describe how you will use the Args for your command
+- `app.rs` to handle the execution of the command
+
+`commands/mod.rs`
+```rust
+
+   pub enum Command {
+    ...
+    /// Descriptive Message for your command
+    Example(ExampleArgs),
+   }
+```
+
+`commands/args.rs`
+```rust 
+
+   #[derive(Debug, Clone, Args)]
+    pub struct ExampleArgs {
+        /// Example arg
+        pub example: String,
+    }
+```
+
+`app.rs` 
+```rust 
+
+    pub fn handle_dot_command(&mut self, line: &str) {
+        ...
+        Ok(cmd) => match cmd.command {
+            ...
+            Command::Example(args) => {
+                println!("{}", args.example);
+            }
+        }
+    }
+
+```
+
+Every single option that is available to CLAP is available here. To facilitate the creation of more helpful help
+messages, please use '///' in your args and command creation, so that CLAP can capture them in the codegen and create their descriptions.
+