nixos/*: cleanup code-escaped manpage urls

Done with

    rg '[a-zA-Z.-]+\([0-9]+\)' -tnix nixos/ -l | xe sd '`\{manpage\}`([a-zA-Z.-]+\([0-9]+\))``' '{manpage}`$1`'

nixos/modules/config/swap.nix

@@ -46,7 +46,7 @@ let
           If not specified, the amount of data to read from `source` will be
           determined by cryptsetup.
 
-          See `{manpage}`cryptsetup-open(8)`` for details.
+          See {manpage}`cryptsetup-open(8)` for details.
         '';
       };
 
@@ -60,7 +60,7 @@ let
           If not specified, the default sector size is determined from the
           underlying block device.
 
-          See `{manpage}`cryptsetup-open(8)`` for details.
+          See {manpage}`cryptsetup-open(8)` for details.
         '';
       };
 

nixos/modules/services/hardware/thinkfan.nix

@@ -259,7 +259,7 @@ in
         description = ''
           Thinkfan settings. Use this option to configure thinkfan
           settings not exposed in a NixOS option or to bypass one.
-          Before changing this, read the `{manpage}`thinkfan.conf(5)``
+          Before changing this, read the {manpage}`thinkfan.conf(5)`
           manpage and take a look at the example config file at
           <https://github.com/vmatare/thinkfan/blob/master/examples/thinkfan.yaml>
         '';