Update README.md

added information on creating and using a conda environment

Author: hburchard

README.md

@@ -8,6 +8,8 @@ Further information about GOTM can be found [here](https://gotm.net).
 
 ### Manual build and install
 
+Note these instruction are writen for the development version of GOTM and the cases described below will only work with this version.
+
 GOTM being written in Fortran requires compilation before it can be used.
 
 Below is provided a short description on how to obtain the code, configure, compile and install GOTM.
@@ -24,6 +26,7 @@ cd GOTM
 Now clone the code to the local machine:
 ```
 git clone --recurse-submodules https://github.com/gotm-model/code.git
+cd code
 ```
 #### Configuring the code for compilation
 
@@ -35,7 +38,9 @@ Furthermore, a Fortran compiler must be installed and discoverable by CMake.
 
 NetCDF has been - and maybe still will be a headache - but it is assumed that NetCDF is installed with Fortran support. For Windows we provide a prebuilt set of libraries.
 
-Configuration is done with cmake - and example being:
+*As an alternative to use system installed programs (CMake, Ninja, Fortran and required libraries) scroll to the bottom of the page(**) and follow the instructions to create a Conda environment with everything required. Then return and continue from here.*
+
+Configuration is done with cmake - an example being:
 ```
 cmake -G Ninja -B build -S code
 ```
@@ -44,25 +49,25 @@ This will create a new folder - build - with the necessary information for actua
 The build system for GOTM provides support for options to pass to the actual compilation. These are provided as extra arguments to the above cmake execution. As and example to include support for ice - use the following:
 
 ```
-cmake -B build -S code -DGOTM_USE_STIM
+cmake -G Ninja -B build -S code -DGOTM_USE_STIM
 ```
-It is always safe to completely remove the build  folder and start all over
+If something goes wrong it is always safe to completely remove the build folder and start all over.
 
 #### Compiling the code
 
 If the cmake command did not result in any errors we are ready to actually compile the code into an executable:
 ```
 cmake --build build
 ```
-This will take a little while but should en up in a compiled GOTM executable in the build/folder. 
+This will take a little while but should en up in a compiled GOTM executable in the build folder. 
 This executable is ready to run but for convinience you might install it in a folder in the PATH on your computer - in which case you can just type - gotm - in any folder.
 
 #### Installing the GOTM executable 
 The installation also is done by CMake:
 ```
 cmake --install build --prefix <folder_in_your_path>
 ```
-To test if it works open a new terminal window and execute - gotm.
+To test if it works open a new terminal window and execute - *gotm*.
 
 #### GOTM test cases 
 GOTM comes with a number of ready to run test cases. There are also in a Git repository and can be obtained like:
@@ -74,3 +79,15 @@ Entering any of the cases folders and just executing - gotm - should run the mod
 An older description is provided here [GOTM homepage](http://www.gotm.net/portfolio/software).
 
 (*) For people who intend to contribute to the GOTM source code a 'fork' is a better solution.
+
+(**) Create a Conda environment.
+If a Conda is not already available install [miniconda](https://www.anaconda.com/docs/getting-started/miniconda/main). Activate the base environment and do (note you must be in the root of the GOTM source code - where the *environment.yml* files is):
+```
+conda env create -f environment.yml
+```
+If successful activate the *gfortran* environment.
+```
+conda activate gfortran
+```
+Return to the configuration instructions give further up.
+