Fix instalation php sury

HowtoPHP.md

@@ -63,6 +63,7 @@ Exemple, si on souhaite seulement php7.3 :
 ~~~
 # apt install wget apt-transport-https
 # wget -O /etc/apt/trusted.gpg.d/php.gpg https://packages.sury.org/php/apt.gpg
+# chmod 644 /etc/apt/trusted.gpg.d/php.gpg
 # echo "deb https://packages.sury.org/php/ stretch main" > /etc/apt/sources.list.d/sury.list
 # cat << EOT > /etc/apt/preferences.d/z-sury
 Package: php* libapache2-mod-php* libpcre2* libzip4*