docs: add java variable conventions to README.md

Author: tom-weelborg

README.md

@@ -85,4 +85,7 @@ The following are lists of conventions that either *should* be followed or *must
     - `static` functions
     - Instance methods
 - `static` Constants:
-  - Names must be `SCREAMING_SNAKE_CASE`
+  - Names must be `SCREAMING_SNAKE_CASE`
+- Instance Attributes and Method Parameters:
+  - Names must be `camelCase`
+  - Should be `final` unless there is a reason to change