docs(configuration): Basic configuration page

Author: tony

docs/configuration/index.md

@@ -1,5 +1,62 @@
+(config)=
+
+(configuration)=
+
 # Configuration
 
+The configuration syntax is declarative and based on tmux's Session, Window and
+Panes hierarchy. Both JSON and YAML is accepted.
+
+## Launching your session
+
+When you have `tmuxp` installed in your environment alongside tmux, you can use:
+
+```console
+$ tmuxp load ./path/to/file
+```
+
+to load your workspace and launch directly into tmux.
+
+In certain cases, tmuxp will try help you when:
+
+- _If your session already exists_: tmuxp will prompt you to re-attach. It does this
+  by checking if the configuration's `session_name` matches a session already
+  running on the same server.
+- _If you're inside a tmux client already_, `tmuxp` will let you create a new session and switch to it, or append the windows to your existing
+  session.
+
+## What's in a config?
+
+1. A session name: `session_name: your session`
+2. A list of _windows_
+3. A list of _panes_ for each window
+
+````{tab} Basics
+
+```yaml
+session_name: My session
+windows:
+- window_name: Window 1
+  panes:
+  - echo "pane 1"
+  - echo "pane 2"
+```
+
+````
+
+````{tab} Smallest possible
+
+```{literalinclude} ../../examples/minimal.yaml
+:language: yaml
+
+```
+
+As of 1.11.x.
+
+````
+
+## Reference and usage
+
 ```{toctree}
 
 environmental-variables