add README for cprover binary

This adds a README for the cprover binary, which includes instructions for
running two sets of verification problems.

Author: kroening

src/cprover/README.md

@@ -0,0 +1,40 @@
+\ingroup module_hidden
+\defgroup cprover cprover
+
+# Folder CPROVER
+
+This contains an experimental encoding from C programs into a Constrained
+Horn Clause (CHC) system.  The satisfiability of the CHC system implies that
+the assertions (as given or generated) hold.  The executable performs the
+encoding and the solving of the CHC system.
+
+The formula generated uses custom operators that model program heaps,
+including memory allocation, memory deallocation, and pointer dereferencing. 
+Owing to these custom operators, standard CHC solvers are not applicable.
+
+To run the encoding and the solver on aws-c-common and coreJSON, first
+ensure that the `cprover` binary is in your `PATH`.  Then perform the
+following steps.
+
+# aws-c-common
+
+```sh
+git clone https://github.com/kroening/aws-c-common
+cd aws-c-common
+git checkout cprover
+cd verification/cprover
+./setup
+./script
+```
+
+# coreJSON
+
+```sh
+git clone https://github.com/kroening/coreJSON
+cd coreJSON
+git checkout cprover
+cd test/cprover
+./setup
+./script
+```
+