Use let<> instead of let*, add documentation

src/kernel_internals/typing/cabs2cil.ml

src/kernel_internals/typing/cfg.ml

src/kernel_internals/typing/mergecil.ml

src/kernel_internals/typing/oneret.ml

src/kernel_internals/typing/unroll_loops.ml

src/kernel_services/analysis/dataflow2.ml

src/kernel_services/analysis/dataflows.ml

src/kernel_services/analysis/stmts_graph.ml

src/kernel_services/ast_data/globals.ml

src/kernel_services/ast_printing/cprint.ml

src/kernel_services/ast_queries/cil.ml

src/kernel_services/ast_queries/cil_const.ml

src/kernel_services/ast_queries/cil_const.mli

src/kernel_services/ast_queries/logic_typing.ml

src/kernel_services/ast_queries/logic_utils.ml

src/kernel_services/ast_transformations/filter.ml

src/kernel_services/visitors/cabsvisit.ml

src/plugins/aorai/aorai_dataflow.ml

src/plugins/wp/cfgInfos.ml

src/plugins/wp/ctypes.ml