Update coding style to include debug prefix for query configs (facebookincubator#10934)

Summary: Pull Request resolved: facebookincubator#10934

Reviewed By: xiaoxmeng

Differential Revision: D62252128

Pulled By: bikramSingh91

fbshipit-source-id: 12acd1ed611a1cf0df4728d1333eef76940ff9a9

Author: bikramSingh91

CODING_STYLE.md

@@ -62,6 +62,11 @@ line width, indentation and ordering (for includes, using directives and etc). 
   their public APIs. Only use test methods in rare edge cases where this is not
   possible. For example, MemoryAllocator::testingSetFailureInjection() is used
   to to inject various memory allocation failures to test error handling paths.
+* Use the **debug** prefix for query configs that are intended for debugging
+  purposes only. These configs may enable expensive checks or disable selective
+  code paths, and are not recommended for use in production environments. For
+  example, `debug_disable_expression_with_peeling` is used to disable peeling
+  optimization employed in expression evaluation.
 
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