Write basic installation instructions.

README.md

@@ -1,3 +1,19 @@
 # STRAW2analysis
 
 All analysis for the STRAW project.
+
+To install first:
+
+* Create a conda virtual environment with the correct Python version.
+
+```commandline
+conda create --name straw2analysis python=3.9
+conda activate straw2analysis
+```
+
+* Next, install all necessary libraries.
+
+```commandline
+cd config
+conda install --file environment.yml
+```