Added descriptions for environment variable overrides to README

README.md

@@ -3,7 +3,7 @@
 The tt-torch project requires environment setup from tt-mlir project. https://github.com/tenstorrent/tt-mlir/
 See documentation of tt-mlir and follow Environment setup. https://docs.tenstorrent.com/tt-mlir/build.html
 
-## Steps:
+## Compile Steps:
 ```
 source env/activate
 cmake -G Ninja -B build
@@ -26,3 +26,16 @@ pre-commit run --all-files
 ```
 
 For more information visit [pre-commit](https://pre-commit.com/)
+
+
+## Controlling Behaviour
+
+You can use the following environment variables to override default behaviour:
+
+| Environment Variable | Behaviour | Default |
+| -------------------- | --------- | --------
+| TT_TORCH_COMPILE_DEPTH | Sets the maximum compile depth, see `tt_torch/tools/utils.py` for options. | `EXECUTE` |
+| TT_TORCH_VERIFY_INTERMEDIATES | Sets whether to verify intermediate tensors agains pytorch when running with compile depth `EXECUTE_OP_BY_OP`. | False |
+| TT_TORCH_CONSTEVAL | Sets whether to enable consteval on the torch fx graph before compiling. | False |
+| TT_TORCH_CONSTEVAL_PARAMETERS | Sets whether to also consteval the parameters, not only the embedded constants. | False |
+| TT_TORCH_ENABLE_IR_PRINTING | Sets whether to enable printing MLIR for all conversion steps from StableHLO to TTNN. Be warned, this forces single core compile, so is much slower. | False |