update README

README.md

@@ -7,15 +7,19 @@ To install RefinedC, please follow the instructions in the [RefinedC
 README](https://gitlab.mpi-sws.org/iris/refinedc/-/blob/master/README.md).
 
 
-To check whether RefinedC is installed correctly, please clone this repository
+To check whether RefinedC is installed correctly, please clone this repository:
 ```
 git clone git-rts@gitlab.mpi-sws.org:msammler/refinedc-tutorial.git
 ```
-change into it:
+Change into it:
 ```
 cd refinedc-tutorial
 ```
-and then run
+Update the opam environment:
+```
+eval $(opam env)
+```
+Run RefinedC:
 ```
 refinedc check tutorial/t01_basic.c
 ```
@@ -28,4 +32,4 @@ This tutorial is work in progress. You can either start by looking at
 [tutorial/t01_basic.c](tutorial/t01_basic.c) or
 [tutorial/VerifyThis/t01_refinements.c](tutorial/VerifyThis/t01_refinements.c).
 
-The files in this repository correspond to commit [5cd9fd78469f3d5408fb2dda21303b773fcd23ac](https://gitlab.mpi-sws.org/iris/refinedc/-/tree/5cd9fd78469f3d5408fb2dda21303b773fcd23ac) of RefinedC.
+The files in this repository correspond to commit [ef732d956054a4c8b6346e8ec08e3e83c58f719a](https://gitlab.mpi-sws.org/iris/refinedc/-/tree/ef732d956054a4c8b6346e8ec08e3e83c58f719a) of RefinedC.