Create configuration.md

Fixes #91

docs/configuration.md

@@ -0,0 +1,20 @@
+# Configuration
+
+Tabby maintains its runtime data in `~/.tabby`, with `~/.tabby/config.toml` serving as its configuration file.
+
+You can modify the path to the data directory by setting the `TABBY_ROOT` variable. For example:
+
+```
+export TABBY_ROOT=/data/tabby
+```
+
+## Example `~/.tabby/config.toml`
+
+```toml
+[[repositories]]
+git_url = "https://github.com/TabbyML/tabby.git"
+```
+
+### `[[repositories]]`
+
+Git repositories integrated into Tabby for prompting/fine-tuning.