Bot Updating Documentation

images/docker-netbootxyz.md

@@ -160,6 +160,7 @@ services:
       - PGID=1000
       - MENU_VERSION=1.9.9 #optional
       - PORT_RANGE=30000:30010 #optional
+      - SUBFOLDER=/ #optional
     volumes:
       - /path/to/config:/config
       - /path/to/assets:/assets #optional
@@ -179,6 +180,7 @@ docker run -d \
   -e PGID=1000 \
   -e MENU_VERSION=1.9.9 `#optional` \
   -e PORT_RANGE=30000:30010 `#optional` \
+  -e SUBFOLDER=/ `#optional` \
   -p 3000:3000 \
   -p 69:69/udp \
   -p 8080:80 `#optional` \
@@ -208,6 +210,7 @@ Docker images are configured using parameters passed at runtime (such as those a
 | `PGID=1000` | for GroupID - see below for explanation |
 | `MENU_VERSION=1.9.9` | Specify a specific version of boot files you want to use from NETBOOT.XYZ (unset pulls latest) |
 | `PORT_RANGE=30000:30010` | Specify the port range tftp will use for data transfers [(see Wikipedia)](https://en.wikipedia.org/wiki/Trivial_File_Transfer_Protocol#Details) |
+| `SUBFOLDER=/` | Specify a sobfolder if running this behind a reverse proxy (IE /proxy/) |
 
 ### Volume Mappings (`-v`)
 
@@ -265,6 +268,7 @@ We publish various [Docker Mods](https://github.com/linuxserver/docker-mods) to
 
 ## Versions
 
+* **29.04.21:** - Rebasing to alpine 3.13, add SUBFOLDER env variable.
 * **01.06.20:** - Rebasing to alpine 3.12.
 * **19.12.19:** - Rebasing to alpine 3.11.
 * **13.12.19:** - Swapping latest tag over to webapp stack for management.