Updated documentation build instructions (Sphinx and Breathe are installed by...

Updated documentation build instructions (Sphinx and Breathe are installed by CMake during configure and probably not found during the first build)

README.md

@@ -64,9 +64,7 @@ Depending on your system configuration, there will be more packages necessary to
 | pip | 2.7 or 3.x |
 | MPI | | Tested with OpenMPI and Mpich
 | SuperLU | 4.3 or 5.x |
-| ----- | ----- | ----- |
 | VirtualEnv | | Install via `pip` |
-| ----- | ----- | ----- |
 | [UG](https://gitlab.dune-project.org/ug/ug) | 3.12.1 | Follow the [IWR Installation Instructions](http://www.iwr.uni-heidelberg.de/frame/iwrwikiequipment/software/ug)
 | [dune-common](https://gitlab.dune-project.org/core/dune-common) | releases/2.4
 | [dune-geometry](https://gitlab.dune-project.org/core/dune-geometry) | releases/2.4
@@ -126,7 +124,7 @@ The following software packages are cross-platform, so you should be able to fin
 
 The documentation of the current `master` branch can be found [online](http://dorie-docs.gitballoon.com) (password: `richards`).
 
-The documentation can be built after DORiE has been properly configured (i.e., by calling `dunecontrol`). Just run
+The documentation can be built after DORiE has been properly configured (i.e., by calling `dunecontrol`). Note that you might have to re-configure DORiE once after installing it, because some dependencies are installed at configure time (e.g. by `dunecontrol --only=dorie configure`). To build the documentation, just run
 
     dunecontrol --only=dorie make doc