feat: savegame transfer docs

docs/_index.md

@@ -26,6 +26,7 @@ Download [latest release](https://github.com/rfg-modding/SyncFaction/releases) a
   * `vanilla` if you want to roll back in time
 * Mods can be placed in app directory manually, old-school way
 * CDN for faster downloads and sharing dev builds
+* Savegame transfer between game versions
 
 ## Non-features
 

docs/dev_mode.md

@@ -35,6 +35,9 @@ Be careful, these options tamper with SF logic and will break your warranty beca
   * `<root>`: open game directory
   * `/data`: open game data directory
   * `/.syncfaction`: open app directory
+* Copy Save
+  * `to Steam`: copy savegame file from GOG directory to Steam directory
+  * `to GOG`: copy savegame file from Steam directory to GOG directory
 
 Things not intended for users:
 

docs/usage.md

@@ -19,6 +19,13 @@ On first run, SF checks your game files. If you had mods before or tampered with
 
 SF will detect if your desktop is light or dark and use according theme automatically.
 
+If you have Steam version, SF will ask if you want to copy your savegame to location where GOG version expects it. This is done only once and is required because the game will be converted to GOG version when you update it. Savegames are always backed up in destination directory.
+
+Savegame files are:
+
+* Steam: `C:\Program Files (x86)\Steam\userdata\STEAMUSERID\667720\remote\autocloud\save\keen_savegame_0_0.sav`
+* GOG: `C:\Users\USER\AppData\Local\GOG.com\Galaxy\Applications\51153410217180642\Storage\Shared\Files\autocloud\save\keen_savegame_0_0.sav`
+
 ## Updates
 
 SF checks for updates of Terraform Patch and RSL and asks user to download and install them. They are absolutely required to play multiplayer and provide common ground for future mods. Normally you don't need to avoid or disable auto-update. If, for some reason, you want app to work entirely offline, want to play vanilla game or apply legacy mods that don't work on top of Terraform - read further.