Add settings documentation

docs/SUMMARY.md

@@ -5,6 +5,7 @@
 - [Installation](installation.md)
 - [Usage](usage.md)
     - [Advanced](advanced.md)
+    - [Settings](settings.md)
     - [TUI](tui.md)
 - [Contributing](contributing.md)
     - [Documentation](documentation.md)

docs/settings.md

@@ -0,0 +1,52 @@
+# Settings
+
+Toot can be configured via a [TOML](https://toml.io/en/) settings file.
+
+> Introduced in toot 0.37.0
+
+> **Warning:** Settings are experimental and things may change without warning.
+
+Toot will look for the settings file at:
+
+* `~/.config/toot/settings.toml` (Linux & co.)
+* `%APPDATA%\toot\settings.toml` (Windows)
+
+Toot will respect the `XDG_CONFIG_HOME` environement variable if it's set and
+look for the settings file in `$XDG_CONFIG_HOME/toot` instead of
+`~/.config/toot`.
+
+## Common options
+
+The `[common]` section includes common options which are applied to all commands.
+
+```toml
+[common]
+# Whether to use ANSI color in output
+color = true
+
+# Enable debug logging, shows HTTP requests
+debug = true
+
+# Redirect debug log to the given file
+debug_file = "/tmp/toot.log"
+
+# Log request and response bodies in the debug log
+verbose = false
+
+# Do not write to output
+quiet = false
+```
+
+## Overriding command defaults
+
+Defaults for command arguments can be override by specifying a `[command.<name>]` section.
+
+For example, to override `toot post`.
+
+```toml
+[command.post]
+editor = "vim"
+sensitive = true
+visibility = "unlisted"
+scheduled_in = "30 minutes"
+```