Mention that aliases are recursive

Instead of duplicating portions of commands that are used identically across many aliases, the user can instead reuse any previously defined aliases.

Author: har7an

src/doc/src/reference/config.md

@@ -335,6 +335,13 @@ r = "run"
 
 Aliases are not allowed to redefine existing built-in commands.
 
+Aliases are recursive:
+
+```toml
+rr = "run --release"
+space_example = "rr -- \"command list\""
+```
+
 #### `[build]`
 
 The `[build]` table controls build-time operations and compiler settings.