Add section about coding style

development-101.md

@@ -44,6 +44,25 @@ The project uses the Gradle Witness to make sure third party dependencies have n
 
     ./update-dependency-pinning.sh
 
+## Coding style
+
+There's an article on the
+[https://code.briarproject.org/briar/briar/-/wikis/code-style](code-style)
+used in the project.
+
+The coding style configuration is checked into version control at
+`.idea/codeStyleSettings.xml` so that it will be picked up automatically by
+Android Studio. AS does not automatically format your files when changing
+them, so you need to remember to use `Ctrl+Alt+L` to format and also
+`Ctrl+Alt+O` for organizing your imports.
+
+If you find that tedious, there are some alternatives:
+* install the Save Actions plugin and configure it to perform those actions
+  while saving your file.
+* Use AS to commit changes to git. If you do so, there's a small preferences
+  button on next to the commit button which let's you configure actions such
+  as 'Reformat code' and 'Optimize imports' that happen at commit time.
+
 ## Coding patterns
 
 ### Patterns for visibility and interfaces