[enh] Optimization + fix typos + add comments

scripts/upgrade

@@ -124,18 +124,24 @@ ynh_replace_string "__YNH_ADMIN_USER__" "$admin" "../conf/local.php"
 # Copy Yunohost specific configuration
 cp ../conf/local.php $final_path/conf
 
-# Do not override ACL configuration file
+# Do not overwrite existing ACL configuration file as it could have user customization's and settings.
+# Create file if it does not exist
+# See https://www.dokuwiki.org/acl#background_info
 if [ ! -f "$final_path/conf/acl.auth.php" ]; then
 	cp ../conf/acl.auth.php $final_path/conf
 fi
 
-# Remove upgrade notification
+# Remove upgrade notification inside Dokuwiki's admin panel
 # See https://www.dokuwiki.org/update_check
 touch $final_path/doku.php
 
 # Remove files not used anymore after upgrade
 # See https://www.dokuwiki.org/install:unused_files
 if [ -f "$final_path/data/deleted.files" ]; then
+
+	# Use a "sub process" to start a new shell to run these commands
+	# Allow to use only one "cd" and to be more efficent
+	(
 		# Move to the dokuwiki installation folder so the "official" commands can be used without adaptation
 		cd $final_path
 
@@ -145,11 +151,7 @@ if [ -f "$final_path/data/deleted.files" ]; then
 
 		# That one works as expected
 		grep -Ev '^($|#)' data/deleted.files | xargs -n 1 rm -fr
-
-	# bash "hack" to move back to the location user was before the last cd made
-	# See http://winterdrake.com/unixlinux-trick-cd-back-to-the-previous-directory/
-	# Should be the script folder of the package
-	cd -
+	)
 fi
 
 # Update all plugins