nixos/lib, doc: remove references to mdDoc (#300738)

* doc: remove references to mdDoc in nixos/doc/manual/development/option-declarations.section.md

* nixos/lib: remove mdDoc in nixos/lib/make-options-doc/default.nix

* nixos/lib: remove mdDoc in nixos/lib/systemd-types.nix

* nixos/lib: remove mdDoc in nixos/lib/systemd-unit-options.nix

* nixos/lib: remove mdDoc in nixos/lib/testing/driver.nix

* nixos/lib: remove mdDoc in nixos/lib/testing/interactive.nix

* nixos/lib: remove mdDoc in nixos/lib/testing/meta.nix

* nixos/lib: remove mdDoc in nixos/lib/testing/name.nix

* nixos/lib: remove mdDoc in nixos/lib/testing/network.nix

* nixos/lib: remove mdDoc in nixos/lib/testing/nodes.nix

* nixos/lib: remove mdDoc in nixos/lib/testing/run.nix

* nixos/lib: remove mdDoc in nixos/lib/testing/testScript.nix

nixos/lib/testing/nodes.nix

@@ -5,7 +5,6 @@ let
     literalExpression
     literalMD
     mapAttrs
-    mdDoc
     mkDefault
     mkIf
     mkOption mkForce
@@ -76,7 +75,7 @@ in
     nodes = mkOption {
       type = types.lazyAttrsOf config.node.type;
       visible = "shallow";
-      description = mdDoc ''
+      description = ''
         An attribute set of NixOS configuration modules.
 
         The configurations are augmented by the [`defaults`](#test-opt-defaults) option.
@@ -88,7 +87,7 @@ in
     };
 
     defaults = mkOption {
-      description = mdDoc ''
+      description = ''
         NixOS configuration that is applied to all [{option}`nodes`](#test-opt-nodes).
       '';
       type = types.deferredModule;
@@ -96,7 +95,7 @@ in
     };
 
     extraBaseModules = mkOption {
-      description = mdDoc ''
+      description = ''
         NixOS configuration that, like [{option}`defaults`](#test-opt-defaults), is applied to all [{option}`nodes`](#test-opt-nodes) and can not be undone with [`specialisation.<name>.inheritParentConfig`](https://search.nixos.org/options?show=specialisation.%3Cname%3E.inheritParentConfig&from=0&size=50&sort=relevance&type=packages&query=specialisation).
       '';
       type = types.deferredModule;
@@ -104,7 +103,7 @@ in
     };
 
     node.pkgs = mkOption {
-      description = mdDoc ''
+      description = ''
         The Nixpkgs to use for the nodes.
 
         Setting this will make the `nixpkgs.*` options read-only, to avoid mistakenly testing with a Nixpkgs configuration that diverges from regular use.
@@ -117,7 +116,7 @@ in
     };
 
     node.pkgsReadOnly = mkOption {
-      description = mdDoc ''
+      description = ''
         Whether to make the `nixpkgs.*` options read-only. This is only relevant when [`node.pkgs`](#test-opt-node.pkgs) is set.
 
         Set this to `false` when any of the [`nodes`](#test-opt-nodes) needs to configure any of the `nixpkgs.*` options. This will slow down evaluation of your test a bit.
@@ -130,7 +129,7 @@ in
     node.specialArgs = mkOption {
       type = types.lazyAttrsOf types.raw;
       default = { };
-      description = mdDoc ''
+      description = ''
         An attribute set of arbitrary values that will be made available as module arguments during the resolution of module `imports`.
 
         Note that it is not possible to override these from within the NixOS configurations. If you argument is not relevant to `imports`, consider setting {option}`defaults._module.args.<name>` instead.
@@ -139,7 +138,7 @@ in
 
     nodesCompat = mkOption {
       internal = true;
-      description = mdDoc ''
+      description = ''
         Basically `_module.args.nodes`, but with backcompat and warnings added.
 
         This will go away.