[README] Add information on how to build the docker image.

README.md

@@ -7,8 +7,10 @@ artificial intelligence based software.
 
 ## Installation
 
-No binaries are provided at the moment. Installation must be done
-by directly compiling the source.
+No binaries are provided at the moment. Installation must be done by either
+compiling the source code or building a [Docker](https://www.docker.com/) image.
+
+### From source code
 
 **Please note:** CAISAR requires the OCaml package manager [opam](https://opam.ocaml.org/),
 v2.1 or higher, which is typically avaible in all major GNU/Linux distributions.
@@ -29,6 +31,15 @@ To run the tests:
 $ make test
 ```
 
+### Docker image
+
+To build a [Docker](https://www.docker.com/) image for CAISAR, do the following:
+```
+$ git clone https://git.frama-c.com/pub/caisar
+$ cd caisar
+$ make docker
+```
+
 ## Usage
 
 To start using CAISAR, please run the command:
@@ -38,8 +49,8 @@ $ caisar --help
 
 ### Property verification
 
-CAISAR can be used to verify properties on neural networks and
-support-vector machines (SVM).
+CAISAR can be used to verify properties on neural networks and support-vector
+machines (SVM).
 
 The prototype command is:
 ```