Update README.md

README.md

@@ -29,7 +29,11 @@ Then download all submodules (this downloads `AMReX` and the string-formatting l
 cd quokka
 git submodule update --init
 ```
-Create a build/ subdirectory and compile Quokka:
+Quokka uses CMake as its build system. If you don't have CMake installed, the easiest way to install it is to run
+```
+pip install cmake
+```
+Now that CMake is installed, create a build/ subdirectory and compile Quokka:
 ```
 mkdir build; cd build
 cmake .. -DCMAKE_BUILD_TYPE=Release
@@ -53,6 +57,9 @@ to compile Quokka for 3D problems.
 
 Have fun!
 
+## CMake
+Quokka uses CMake for its build system. If you don't have CMake installed already, you can simply `pip install cmake` or use another [installation method](https://cliutils.gitlab.io/modern-cmake/chapters/intro/installing.html). If you are unfamiliar with CMake, [this tutorial](https://hsf-training.github.io/hsf-training-cmake-webpage/) may be useful.
+
 ## Running on GPUs
 By default, Quokka compiles itself to run only on CPUs. If you want to run on NVIDIA GPUs, re-build Quokka with the following options:
 ```
@@ -64,4 +71,4 @@ The compiled test problems are in the test problem subdirectories in `build/src/
 **AMD or Intel GPUs:** Running on AMD or Intel GPUs is currently experimental and has *not been tested* by the Quokka developers. AMReX is currently undergoing rapid advances in its support for GPUs from these vendors, so please get in touch by starting a Discussion before attempting this.
 
 ## Problems?
-If you run into problems, please start a [Discussion](https://github.com/BenWibking/quokka/discussions) for technical support. If you discover a bug, please let us know by opening an [Issue](https://github.com/BenWibking/quokka/issues).
+If you run into problems, please start a [Discussion](https://github.com/BenWibking/quokka/discussions) for technical support. If you discover a bug, please let us know by opening an [Issue](https://github.com/BenWibking/quokka/issues).