[CI:DOCS] README: drop sudo

Running the script from the README does not require root privileges.
The text seems to predate Buildah's rootless support.  It was brought to
my attention during a presentation last week where an attendee asked
whether Buildah requires root privileges after reading the README.

Signed-off-by: Valentin Rothberg <[email protected]>

README.md

@@ -99,7 +99,7 @@ buildah commit "$ctr1" "${2:-$USER/lighttpd}"
 EOF
 
 $ chmod +x lighttpd.sh
-$ sudo ./lighttpd.sh
+$ ./lighttpd.sh
 ```
 
 ## Commands