updated contributing page with more information

CONTRIBUTING.md

@@ -1,8 +1,19 @@
 # Contributing to Olive
 
+Thank you for your interest in contributing to Olive! In order to keep the code as readable and maintainable as possible, code submitted should abide by the following standards:
+
 ### Standards
 
 When contributing to Olive, it's recommended to use the following rules:
 
-* [Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html)
-* 120 column limit
+* The code style generally follows the [Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html) including, but not limited to:
+** Indentation is 2 spaces wide, spaces only (no tabs)
+** `lowercase_underscored_variable_names`
+** `lowercase_underscored_functions()` or `SentenceCaseFunctions()`
+** `class SentenceCaseClassesAndStructs {}`
+** `kSentenceCaseConstants` prepended with a lowercase `k`
+** `UPPERCASE_UNDERSCORED_MACROS` for variables or same style as functions for macro functions
+** `class_member_variables_` end with a `_`
+* 100 column limit (where it doesn't impair readability)
+* Unix line endings (only LF no CRLF)
+* Javadoc documentation where appropriate