Update readme

README.md

@@ -1,5 +1,7 @@
-## gandi-live-dns-rust
+## Gandi Live Dns Rust <!-- omit in toc -->
+
 <!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
+
 [![Contributors](https://img.shields.io/badge/all_contributors-1-orange.svg?label=contributors)](#contributors) <!-- ALL-CONTRIBUTORS-BADGE:END -->
 [![tests](https://img.shields.io/github/actions/workflow/status/SeriousBug/gandi-live-dns-rust/test.yml?label=tests&branch=master)](https://github.com/SeriousBug/gandi-live-dns-rust/actions/workflows/test.yml)
 [![Test coverage report](https://img.shields.io/codecov/c/github/SeriousBug/gandi-live-dns-rust)](https://codecov.io/gh/SeriousBug/gandi-live-dns-rust)
@@ -19,6 +21,23 @@ program can update both IPv4 and IPv6 addresses for one or more domains and
 subdomains. It can be used as a one-shot tool managed with a systemd timer
 or cron, or a long-running process that reschedules itself.
 
+## Table of Contents <!-- omit in toc -->
+
+- [Usage](#usage)
+  - [System packages](#system-packages)
+  - [Prebuilt binaries](#prebuilt-binaries)
+  - [With docker](#with-docker)
+  - [From source](#from-source)
+- [Automation](#automation)
+  - [By running as a background process](#by-running-as-a-background-process)
+    - [Skipped updates](#skipped-updates)
+  - [With a Systemd timer](#with-a-systemd-timer)
+- [Development](#development)
+  - [Local builds](#local-builds)
+  - [Making a release](#making-a-release)
+- [Alternatives](#alternatives)
+- [Contributors](#contributors)
+
 ## Usage
 
 The Gandi Live DNS API is rate limited at 30 requests per minute. This program
@@ -90,15 +109,23 @@ docker run --rm -it -v $(pwd)/gandi.toml:/gandi.toml:ro seriousbug/gandi-live-dn
 Or with a `docker-compose.yml` file, add it in the arguments:
 
 ```yml
-  gandi-live-dns:
-    image: seriousbug/gandi-live-dns-rust:latest
-    restart: always
-    volumes:
-      - ./gandi.toml:/gandi.toml:ro
-    # Repeat the update every day
-    command: --repeat=86400
+gandi-live-dns:
+  image: seriousbug/gandi-live-dns-rust:latest
+  restart: always
+  volumes:
+    - ./gandi.toml:/gandi.toml:ro
+  # Repeat the update every day
+  command: --repeat=86400
 ```
 
+#### Skipped updates
+
+In background process mode, the tool will avoid sending an update to Gandi if
+your IP address has not changed since the last update. This only works so long
+as the tool continues to run, it will send an update when restarted even if your
+IP address has not changed. You can also override this behavior by adding
+`always_update = true` to the top of your config file.
+
 ### With a Systemd timer
 
 The `Packaging` folder contains a Systemd service and timer, which you can use