Update readme. (#312)

* Update readme.

* Copy Cargo.toml commands in README.

README.md

@@ -33,12 +33,20 @@ Checkout [orml-workshop](https://github.com/xlc/orml-workshop) for example usage
 ### Makefile targets
 
 - `make check`
-	- Type check the code, without std feature, exclduing tests.
+	- Type check the code, without std feature, excluding tests.
 - `make check-tests`
 	- Type check the code, with std feature, including tests.
 - `make test`
 	- Run tests.
 
+### `Cargo.toml`
+
+ORML use `Cargo.dev.toml` to avoid workspace conflicts with project cargo config. To use cargo commands in ORML workspace, create `Cargo.toml` by running
+
+- `cp Cargo.dev.toml Cargo.toml`, or
+- `make Cargo.toml`, or
+- change the command to `make dev-check` etc which does the copy. (For the full list of `make` commands, check `Makefile`)
+
 # Projects using ORML
 
 _In alphabetical order_