Add nginx README and configuration docs back

docs/README.md

@@ -1,3 +1,21 @@
 # Ingress documentation and examples
 
 This directory contains documentation.
+
+## File naming convention
+
+Try to create a README file in every directory containing documentation and index
+out from there, that's what readers will notice first. Use lower case for other
+file names unless you have a reason to draw someones attention to it.
+Avoid CamelCase.
+
+Rationale:
+
+* Files that are common to all controllers, or heavily index other files, are
+named using ALL CAPS. This is done to indicate to the user that they should
+visit these files first. Examples include PREREQUISITES and README.
+
+* Files specific to a controller, or files that contain information about
+various controllers, are named using all lower case. Examples include
+configuration and catalog files.
+