Update README.md - add brief descriptions of current features

Author: olivialynn

README.md

@@ -11,3 +11,18 @@
 [![Read The Docs](https://img.shields.io/readthedocs/lsdb-rubin)](https://lsdb-rubin.readthedocs.io/)
 
 Suite of utilities for interacting with Rubin LSST data within LSDB.
+
+## LSST tract/patch search
+Use LSDB to search catalogs by LSST tract and/or patch.
+```python
+gaia.tract_patch_search(skymap=lsst_skymap, tract=tract_index)
+```
+See the [demo notebook](https://github.com/astronomy-commons/lsdb-rubin/blob/main/docs/notebooks/tract_patch_search.ipynb).
+
+## Plot a LSST light curve
+LSST light curves can be tricky to plot, so we've provided an easy method for a single light curve.
+
+```python
+plot_light_curve(dia_object.iloc[0]["diaObjectForcedSource"])
+```
+See the [demo notebook](https://github.com/astronomy-commons/lsdb-rubin/blob/main/docs/notebooks/plot_light_curves.ipynb).