add --no-dev parameter to composer

doc/Update.md

@@ -21,7 +21,7 @@ You can get the latest changes at any time with
 
     cd path/to/friendica
     git pull
-    bin/composer.phar install
+    bin/composer.phar install --no-dev
 
 The addon tree has to be updated separately like so:
 
@@ -69,4 +69,4 @@ DROP TABLE <table_name>;
 RENAME TABLE <table_name>_new TO <table_name>;
 ```
 
-This method is slower overall, but it is better suited for large numbers of duplicates.
+This method is slower overall, but it is better suited for large numbers of duplicates.