Update README.md with latest features

Update README.md to reflect that we're using now three programs and
also update the Usage section with the current command line options.

Signed-off-by: Sergio Lopez <slp@redhat.com>

Author: slp

README.md

@@ -6,19 +6,48 @@
 
 - `muvm-guest`: acts as an entrypoint inside the microVM to set up the environment for running your program.
 
+- `muvm-server`: a server listening for requests to run additional programs. This allows you to run multiple graphical applications inside the same microVM.
+
 ## Using
 
 ``` sh
-
-Usage: muvm [OPTIONS] COMMAND [COMMAND_ARGS...]
-OPTIONS:
-        -h    --help                Show help
-              --net=NET_MODE        Set network mode
-              --passt-socket=PATH   Instead of starting passt, connect to passt socket at PATHNET_MODE can be either TSI (default) or PASST
-
-COMMAND:      the command you want to execute in the vm
-COMMAND_ARGS: arguments of COMMAND
-
+Usage: muvm [-c=CPU_LIST]... [-e=ENV]... [--mem=MEM] [--vram=VRAM] [--passt-socket=PATH] [-p=
+SERVER_PORT] [-f=FEX_IMAGE]... COMMAND [COMMAND_ARGS]...
+
+Available positional items:
+    COMMAND                  the command you want to execute in the vm
+    COMMAND_ARGS             arguments of COMMAND
+
+Available options:
+    -c, --cpu-list=CPU_LIST  The numerical list of processors that this microVM will be bound to.
+                                     Numbers are separated by commas and may include ranges. For
+                                     example: 0,5,8-11.
+                             [default: all logical CPUs on the host, limited to performance cores
+                                 (if applicable)]
+    -e, --env=ENV            Set environment variable to be passed to the microVM
+                                     ENV should be in KEY=VALUE format, or KEY on its own to inherit
+                                     the current value from the local environment
+        --mem=MEM            The amount of RAM, in MiB, that will be available to this microVM.
+                                     The memory configured for the microVM will not be reserved
+                                     immediately. Instead, it will be provided as the guest demands
+                                     it, and both the guest and libkrun (acting as the Virtual
+                                     Machine Monitor) will attempt to return as many pages as
+                                     possible to the host.
+                             [default: 80% of total RAM]
+        --vram=VRAM          The amount of Video RAM, in MiB, that will be available to this
+                             microVM.
+                                     The memory configured for the microVM will not be reserved
+                                     immediately. Instead, it will be provided as the guest demands
+                                     it, and will be returned to the host once the guest releases
+                                     the underlying resources.
+                             [default: same as the total amount of RAM in the system]
+        --passt-socket=PATH  Instead of starting passt, connect to passt socket at PATH
+    -p, --server-port=SERVER_PORT  Set the port to be used in server mode
+                             [default: 3334]
+    -f, --fex-image=FEX_IMAGE  Adds an erofs file to be mounted as a FEX rootfs.
+                                     May be specified multiple times.
+                                     First the base image, then overlays in order.
+    -h, --help               Prints help information
 ```
 
 ## Running graphical applications