Add naming guidelines from wiki

Documentation/Specification/Naming_Guidelines.md

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+# Plus Codes and Open Location Code Naming Guidelines
+
+## Why have guidelines?
+
+These guidelines are offered so that people see a consistent reference to the codes and technology.
+This will make it easier for them to understand what they are being shown or asked for.
+
+We have chosen two names - one for the technology and one for the actual codes.
+The name for the codes reflects and reinforces the importance of the plus symbol, which is how the codes can be recognised.
+
+## Plus Codes
+
+When referring to Plus Codes in English, the **only** term that should be used is "Plus Code", in Title Case.
+
+Some examples of usage are:
+* "My Plus Code is CX37+M9."
+* "I gave your Plus Code to the cab driver and he found the way without any problems."
+* "Will the postcard arrive if I put your Plus Code as the address?"
+* "Enter your Plus Code or street address here."
+
+### Global and local codes
+
+Codes that can be decoded to a lat/lng on their own, e.g. 796RWF8Q+WF are referred to as global codes.
+
+The shortened codes, e.g., WF8Q+WF are referred to as local codes, because they work within a local area.
+
+## Open Location Code
+
+When discussing with organisations or developers, refer to the library, algorithm and technology as "Open Location Code".
+This can be abbreviated to OLC, is capitalised, and shouldn't be translated.
+
+It shouldn't be used to refer to the actual codes - don't say "Open Location Codes" for example.
+
+## Summary
+
+Having consistent names and presentation will make it easier for people to recognise what is meant, and make it easier for them to use and benefit from the project.
+