feat: Added Darkness falls 21 support (#231)

scripts/Mods/darkness_falls.sh

@@ -11,10 +11,12 @@ if [ "${DARKNESS_FALLS_URL}" != "False"  ]; then
 else
     # Change DL_LINK depending on 7 days to die branch version
     if [ "${VERSION}" == 'stable' ] || [ "${VERSION}" == 'public' ]; then
-        echo "[Darkness Falls] No version found compatible with version ${VERSION}"
+        echo "[Darkness Falls] No version found compatible with version ${VERSION}, you need to choose a version. Example: alpha21"
         echo "[Darkness Falls] If there is a compatible version check -> https://community.7daystodie.com/topic/4941-darkness-falls-they-mostly-come-out-at-night/ and install it manually or using DARKNESS_FALLS_URL"
         echo "[Darkness Falls] Omitting installation"
         exit
+    elif [ "${VERSION::7}" == 'alpha21' ]; then
+        DL_LINK="https://dev.azure.com/KhaineUK/_git/DarknessFallsA21"
     elif [ "${VERSION::7}" == 'alpha20' ]; then
         DL_LINK="https://dev.azure.com/KhaineUK/_git/DarknessFallsA20"
     else