Added Forge README

fabric/README.md

@@ -6,7 +6,7 @@ version of Fabric you wish to install. You can find the list of versions
 
 # Environment variables
 The two possible environment variables are `XMS` and `XMX`. These specify the
-initial RAM & maximum RAM usage, respectively. Only `XMS` is required; `XMX` is
+initial RAM & maximum RAM usage respectively. Only `XMS` is required; `XMX` is
 just set to the same value as `XMS` if not specified. You must specify them as
 a number, e.g. `XMS=4`. This number represents a quantity of gigabytes.
 

forge/README.md

@@ -0,0 +1,49 @@
+# Build arguments
+Two build arguments are required, namely `MC_VERSION` and `FORGE_VERSION`.  You
+can find your required versions [here](https://files.minecraftforge.net/).
+Then, you can specify them in the `.env` file:
+
+```
+MC_VERSION=1.16.4
+FORGE_VERSION=35.1.4
+```
+
+# Environment variables
+The two possible environment variables are `XMS` and `XMX`. These specify the
+initial RAM & maximum RAM usage respectively. Only `XMS` is required; `XMX` is
+just set to the same value as `XMS` if not specified. You must specify them as
+a number, e.g. `XMS=4`. This number represents a quantity of gigabytes.
+
+# Mount points
+There a three useful mount points defined:
+
+* `/mc/config`: this is where all server config files reside.
+* `/mc/config/mods`: this is where all mods should be placed.
+* `/mc/worlds`: this is where the world files are stored.
+
+You can mount these directories somewhere in the host file system by specifying
+the mount paths in the `.env` file. These can be both absolute or relative
+paths.
+
+# Other config variables
+The only other config variable is `PORT`. This specifies on what port your
+server will be discoverable over the internet. The default Minecraft port is
+`25565`.
+
+# Java flags
+I use the Java flags defined
+[here](https://aikar.co/2018/07/02/tuning-the-jvm-g1gc-garbage-collector-flags-for-minecraft/).
+If you don't agree with this decision, you can change the `ENTRYPOINT` at the
+end of the `Dockerfile` to the following:
+
+```
+ENTRYPOINT java \
+-Xms"${XMS}G" \
+-Xmx"${XMX:-$XMS}G" \
+-jar "$FORGE_JAR" \
+--universe /mc/worlds \
+--nogui
+```
+
+This will only use the flags absolutely necessary, while still allowing you to
+tweak the memory variables.