Add doc string steps

src/partitioner.cpp

@@ -223,17 +223,28 @@ Given target assignments (tass) for the instructions, generate run_on_target mod
 automatically. Input graph should be uncompiled migraphx program. target assignments (tass) map
 should have a map of instruction to target_id. Instructions that are not inside tass map are
 considered to be targeted for the "Ref" by default. params, literals and other builtins shouldn't be
-part of the tass, only compute and reshape instructions should be part of tass. Copy, sync and alloc
-instructions would be generated by compiler at later stage, so those shouldn't be considered.
+part of the tass, only compute and reshaper instructions should be part of tass. Copy, sync and
+alloc instructions would be generated by compiler at later stage, so those shouldn't be considered.
 (TODO): CustomOps may require special handling.
 
-
-Identify subgraph boundaries,  Ref is used for instructions that do not have assignments
+Step 1:
+Identify subgraph boundaries
+Ref is used for instructions that do not have assignments.
+Boundaries can happen in following cases.
 1.  Ref --> Target X --> Ref
-2.  Ref --> Target X --> Target 2
+2.  Ref --> Target X --> Target Y
 3.  Target X --> Target Y --> Target Z , in this case target X and target Z can be same
 4.  Target X --> "@return"
 5.  Target X --> Ref --> "@return"
+
+Each of those identified regions could have futher nested sub modules which needs to be handled
+separately.
+
+Step 2:
+Collect parameters and return instructions for the subgraphs identified in Step 1.
+
+Step 3:
+Create modules using information collected in step 2 and insert run_on_target instructions.
 */
 
 void partition(migraphx::module_ref mm,