Linux: Improve web root path detection or/and better document how to specify it

[colemar]

• Transmission version: transmission-daemon 4.0.3 (6b0e49bbb2)
• Transmission Web Control Installation script version: 1.2.3

I got transmission from
https://github.com/transmission/transmission/releases/download/4.0.3/transmission-4.0.3.tar.xz
then proceeded to build it as explained in
https://github.com/transmission/transmission#building-a-transmission-release-from-the-command-line
After make install the web root was /usr/local/share/transmission/public_html/ (notice no web folder).
Downloaded latest install-tr-control.sh and immediately noticed that at line 109 it assumes that transmission web root path ends in web: WEB_FOLDER="$ROOT_FOLDER/web"

My workaround was

cd /usr/local/share/transmission
ln -s public_html web

root@pih:/usr/local/share/transmission# ls -l
total 12
drwxr-xr-x 3 root root 4096 Apr 21 14:20 ./
drwxr-xr-x 7 root root 4096 Apr 20 14:55 ../
drwxr-xr-x 3 root root 4096 Apr 21 14:19 public_html/
lrwxrwxrwx 1 root root   11 Apr 21 14:20 web -> public_html/