The Release folder contains the folder and files that will be uploaded to web sites. Files include not only the vpk file (the actual addon file), but also images and text files that can be used for describing the addon on web pages.
Create the Release folder:
Within the "workspace" folder, create the folder: 03 Release
Note the "03" at the start of the name. I use that so the workspace folders are listed in this order: 01 Setup, 02 Source, 03 Release
The only required folder within the Release folder is the VPK folder. It should be named exactly as the vpk file will be named (without the ".vpk" extension), because it will be used when creating the final vpk file. The VPK folder contains all of the files that will replace those found in the game.
I tend to store screenshots and readme-type text files in the Release folder (but not inside the VPK folder) that I will later use on a download web page for the addon.
Within the Release folder, create a folder (referred to as the VPK folder hereafter) named exactly as the vpk file will be named (without the ".vpk" extension). For example: Rochelle_JillValentineCasual
Within the VPK folder, create the folder tree: materials\models\survivors
Also within the VPK folder, create the folder tree: models\survivors