Revise docs and struct name; add basic MPI test

test/src/solution/methods/ProgressiveHedging/usage_test.jl

@@ -0,0 +1,16 @@
+# UnitCommitment.jl: Optimization Package for Security-Constrained Unit Commitment
+# Copyright (C) 2020, UChicago Argonne, LLC. All rights reserved.
+# Released under the modified BSD license. See COPYING.md for more details.
+
+using MPI
+
+function solution_methods_ProgressiveHedging_usage_test()
+    basedir = dirname(@__FILE__)
+    @testset "ProgressiveHedging" begin
+        mpiexec() do exe
+            return run(
+                `$exe -n 2 $(Base.julia_cmd()) --project=test $basedir/ph.jl`,
+            )
+        end
+    end
+end