[USGS-R#7] update readme with container instructions

README.md

@@ -1,3 +1,18 @@
 # drb_gridmet_tools
 
 Repository with functions to aggregate raster data from pixel grid to vector aoi (hru polygon grid, polylines). This repository heavily relies on [grd2shp_xagg](https://github.com/rmcd-mscb/grd2shp_xagg) library, by [rmcd-mscb](https://github.com/rmcd-mscb)
+
+# running the code
+The pipeline specified in `Snakefile` will aggregate gridmet data to the polygons in the geo file specified. Currently, it's set up to pull the gridmet data from the start of the data archive (1979-01-01) to the present day.
+
+## running with Docker
+```
+docker run jsadler2/gridmet-agg:v0.1 snakemake
+```
+
+## running with Singularity
+We have to specify the full path to `snakemake` because it is not part of the system PATH in the Singularity container
+```
+singularity pull jsadler2/gridmet-agg:v0.1
+singularity exec gridmet-agg_v0_1.sif /opt/conda/snakemake
+```