After editing rish by placing the text "com.termux" in it, put both rish and rish_shizuku.dex in a folder lets call termuxrish into the main area of /sdcard. From there go to termux and do the following. Read carefully!!! 

mv /sdcard/termuxrish/rish $PATH
mv /sdcard/termuxrish/rish_shizuku.dex $PATH
cd $PATH
chmod +x rish
chmod +x rish_shizuku.dex
cd $HOME
rish


If you followed everything correctly you should be a shell user now.