Updated readme, added compatability for Singularity build process

Makefile

@@ -1,9 +1,8 @@
-APPTAINER ?= apptainer
+APPTAINER ?= singularity
 OVERLAY_DIR ?= ./overlay
 NUM_THREADS ?= $(shell grep -c processor /proc/cpuinfo)
 
 UID := $(shell id -u)
-GID := $(shell id -g)
 
 .DEFAULT_GOAL := mobileinsight.sif
 

README.md

@@ -1,13 +1,20 @@
 MobileInsight Apptainer
 =======================
 
-Single launch binary for MobileInsight in a Ubuntu 22.04 portable container.
+Single launch binary for [MobileInsight](https://github.com/mobile-insight) in
+a Ubuntu 22.04 SIF portable container.
 
 Dependencies
 ------------
 
-The host side only needs `apptainer` or `singularity` to function. A gui is
-needed to launch the log viewer.
+Either one of the following dependencies is needed to run or build SIF images:
+
+- [Apptainer](https://apptainer.org/)
+- [Singularity](https://sylabs.io/singularity/)
+
+To use the `make run` command, the overlay Linux kernel module must also be
+available on the system. This allows you to make changes to the SIF file using
+an overlay filesystem.
 
 Usage
 -----
@@ -25,13 +32,7 @@ $ ./mobileinsight.sif bash
 
 Examples are stored in /opt/mobileinsight-examples.
 
-Building
---------
-
-To build the apptainer, the following dependencies are needed on the host
-machine:
-
-1. Apptainer or Singularity
-2. Docker
+Build
+-----
 
 Run `make mobileinsight.sif` to build the apptainer image.