feat: Add example

BREAKING CHANGE. This should be the initial release.

README.md

@@ -1,2 +1,22 @@
-This is pysphereproj
+# PySphereProj
 
+This is a simple package made of 3d interpolators (CIC based) and 3d to healpix projector.
+
+Everything is contained in the package `sphereproj`.
+
+Here is a short example for spherical projection:
+
+```python
+
+import sphereproj
+import numpy as np
+
+N = 256
+Nside=128
+rho = np.random.randn(N,N,N)
+
+result = sphereproj.spherical_projection(Nside, density, 0, 128, integrator_id=1)
+# min_distance, max_distance, progress=1, integrator_id=0, shifter=None, booster=-1)
+
+
+```