[Expression Language] Number of backslashes to escape a backslash

[devojifr]

To escape a backslash in a string, we must use 3 backslashes before the backslash itself.
The documentation points out we need to escape by 4 backslashes the backslash. It could be confusing, the total would 5 backslashes.

[xabbuh]

Good catch, thanks @devojifr.