README.md: update and add details

README.md

 # COLIBRI
 
-## Special directories
+## Bundle
 
-`Bin/` and `Src/` directories are copied from their respective
-repositories using the `release_colibri_opensource.sh` script found in
-`gatel/Src`'s original repository. They should be considered read-only
-here.
+The command `make bundle` will create a relocalisable directory named
+`bundle` containing the ` colibri`  executables.
 
-## Bundle
+## Dependencies
+
+In addition to the =Eclipse (CLP)= environment that is
+distributed within the bundle, the `colibri` solver relies
+on two auxiliary libraries: 
+
+- `float_util.so` 
+- `simplex_ocaml.so`
+	
+The simplex library needs to link to `libgmp.so`, which can
+be installed using your distribution (e.g. on Debian from
+the ` libgmp-dev` package).
+
+In order to build `simplex_ocaml.so`, it is necessary to
+have `opam` installed and configured, in order to install
+the following OCaml modules:
 
-In order to create a bundle of everything needed to run COLIBRI. run
-`./compile_colibri.sh` then run `./bundle.sh` it will create
-a relocalisable directory `bundle`.
+   - dune
+   - fmt
+   - gen
+   - menhir
+   - ocplib-simplex
+   - parsexp
+   - spelll
+   - uutf
+   - zarith
+
+The exact versions required are listed in `.gitlab-ci.yml`.
 
 ## Compilation on linux
 
-The up-to-date information could be found in `.gitlab-ci.yml`.
+The command `make` builds all the libraries and executables.
+
+The `Makefile` can be parameterized by two environment
+variables, `BUNDLE` (which is the directory where the bundle
+is created), and `ECL_VERSION`, which indicates which
+version of the Eclipse library should be used (see `Makefile`
+for details).
 
 ## Compilation on windows
 
 The compilation is helped by using
 https://fdopen.github.io/opam-repository-mingw/, it will install ocaml
-compiler but also mingw for the C part. Use ocaml-env to setup the
+compiler but also mingw for the C part. Use `ocaml-env` to setup the
 environement for the compilation. Then the compilation is the same
 than for linux.
 
+## Remarks
+
+`Bin/` and `Src/` directories are copied from their respective
+repositories using the `release_colibri_opensource.sh` script found in
+`gatel/Src`'s original repository. They should be considered read-only
+here.
+
 ## LICENCE
 
 This is the open-source colibri distribution.