cp: add more information link (#5853)

pages.it/linux/cp.md

@@ -1,6 +1,7 @@
 # cp
 
 > Copia file e cartelle.
+> Maggiori informazioni: <https://www.gnu.org/software/coreutils/cp>.
 
 - Copia un file in un'altra posizione:
 

pages/linux/cp.md

@@ -1,6 +1,7 @@
 # cp
 
 > Copy files and directories.
+> More information: <https://www.gnu.org/software/coreutils/cp>.
 
 - Copy a file to another location: