Move Infrastructure section to the end, and other minor tweaks.

samba-functionality/overview.md

@@ -253,7 +253,7 @@ available for direct use as well.
 
 ### [LDB](https://ldb.samba.org/)
 
-LDB is not just the basis for the AD DC's database
+LDB (LDAP-like Database) is not just the basis for the AD DC's database
 [sam.ldb](../protocols-and-subsystems/sam.ldb) in Samba), it is also a
 stand-alone library for wider use.