Basic structure of the extension & package

CONTRIBUTING.md

@@ -0,0 +1,38 @@
+# Contributing guide
+
+## How to add new functions
+
+Try to put as little logic in the SQL extension as possible and
+just use it as a wrapper to the Python module functionality.
+
+### Python
+
+...
+
+### SQL
+
+* Generate a **new subfolder version** for `sql` and `test` folders to define the new functions and tests
+  * Use symlinks to avoid file duplication between versions that don't update them
+  * Add or upgrade your SQL server functions
+  * Create tests for the client and server functions -- at least, to check that those are created
+
+* Generate the **upgrade and downgrade files** for the extension for both client and server
+
+* Update the control files and the Makefiles to generate the complete SQL file for the new created version
+  * These new version file (`crankshaft--X.Y.Z.sql`)
+    must be pushed and frozen. You should add it to the `.gitignore` file.
+
+* Update the public docs! ;-)
+
+## Naming things
+
+# SQL
+
+Use snake case (i.e. `snake_case` and not `CamelCase`) for all
+functions. Prefix functions intended for public use with `cdb_`
+and private functions (to be used only internally inside
+the extension)  with `_cdb_`.
+
+# Python
+
+...