treewide: fix typos and other minor issues

mail-server/dovecot.nix

@@ -145,7 +145,7 @@ let
     lib.filterAttrs (_: v: v ? "specialUse" && v.specialUse == "Junk") cfg.mailboxes
   );
   junkMailboxNumber = builtins.length junkMailboxes;
-  # The assertion garantees there is exactly one Junk mailbox.
+  # The assertion guarantees there is exactly one Junk mailbox.
   junkMailboxName = if junkMailboxNumber == 1 then builtins.elemAt junkMailboxes 0 else "";
 
   mkLdapSearchScope =
@@ -206,7 +206,7 @@ in
       };
     };
 
-    # for sieve-test. Shelling it in on demand usually doesnt' work, as it reads
+    # for sieve-test. Shelling it in on demand usually doesn't work, as it reads
     # the global config and tries to open shared libraries configured in there,
     # which are usually not compatible.
     environment.systemPackages = [