clarify build instructions

timelapsepi/README.md

@@ -2,13 +2,12 @@
 
 This folder manages how disk images are created which can be installed on SD cards to boot Raspberry Pis. For more information checkout https://github.com/guysoft/CustomPiOS.
 
-To create a new disk image, run the following from Linux (after going through the CustomPiOS setup steps - specifically, you may need to install the following: `sudo apt-get install qemu-user-static`). This will create a disk image in `src/workspace/*.img`. The created image can be installed onto an SD card via the [Raspberry Pi Imager](https://www.raspberrypi.org/software/).
+1. Follow steps in the [CustomPiOS docs](https://github.com/guysoft/CustomPiOS?tab=readme-ov-file#how-to-use-it). This will download the latest OS .img file and prepare it along with other build related files. Optionally: Download another image variant via:
 
-```
-cd src/ && sudo ./build_dist
-```
-
-Optionally: Download another image variant before invoking `build_dist`
-```
+```bash
 cd src/image/ && wget https://downloads.raspberrypi.org/raspios_lite_armhf/images/raspios_lite_armhf-2021-05-28/2021-05-07-raspios-buster-armhf-lite.zip && cd ../../
 ```
+
+2. install required software: `sudo apt-get install qemu-user-static p7zip-full`
+3. start build: `cd src/ && sudo ./build_dist`. This will create a disk image in `src/workspace/*.img`.
+4. The created image can be installed onto an SD card via the [Raspberry Pi Imager](https://www.raspberrypi.org/software/).