add info about bootable images

README.md

@@ -12,3 +12,14 @@ Tested as primary OS on following devices:
   * *Raspberry Pi Zero W*
 
 Docker images available at [Docker Hub](https://hub.docker.com/u/jpalus).
+
+Bootable images:
+
+**Raspberry Pi**
+* `raspberry-pi-pld-linux-base-armv6hl` bootable on Raspberry Pi Zero W and Raspberry Pi 2, `raspberry-pi-pld-linux-base-armv7hnl` bootable on Raspberry Pi 2
+* requires at least 2GB of storage
+* write image to SD card ie:
+```
+xz -dc raspberry-pi-pld-linux-base-armv7hnl-20211102.img.xz | dd of=/dev/mmcblk1 bs=4M
+```
+* root password: *pld*