docs: add description of samplers

docs/source/sampler/index.rst

@@ -6,11 +6,11 @@ This module hosts functionality for sampling methods.
 
 Currently implemented classes are:
 
-* :class:`.LHS`:
+* :class:`.LHS`: Latin hypercube sampling.
 
-* :class:`.MetroplisHastings`:
+* :class:`.MetropolisHastings`: Metropolis Hastings sampling.
 
-* :class:`.Saltelli`:
+* :class:`.Saltelli`: Saltelli's version of Sobol' sampling.
 
 .. toctree::
    :maxdepth: 1