step 7: harden docs and prepare beta

docs/GETTING_STARTED.md

@@ -0,0 +1,19 @@
+# Getting Started
+
+Install with `uv add dpg-gauges`, then import as `import dpg_gauges as dpgg`.
+
+Create gauges inside a Dear PyGui context:
+
+```python
+import dearpygui.dearpygui as dpg
+import dpg_gauges as dpgg
+
+dpg.create_context()
+with dpg.window(label="Dashboard"):
+    dpgg.digital_gauge(tag="speed", label="Speed", value=72, unit="km/h")
+
+dpgg.set_value("speed", 88)
+```
+
+All widget creation and runtime updates are Dear PyGui GUI-thread operations. If telemetry is
+produced in a worker thread, store the latest value and apply it from a GUI frame callback.