docs: stop citing internal documents from public comments

Three comments named a file in the internal repo: a contract, a design
guide, and a user-research document with section numbers. A filename plus
a section tells a reader what to ask for, which is the escape the marker
convention exists to prevent.

Each comment now states the requirement on its own terms. The render-node
requirement carries a decision marker; the other two have no decision
behind them, so they cite nothing.

apps/nesdoctor/src/ask.rs

@@ -28,11 +28,12 @@ pub struct Answers {
     /// currently reach are already doing for themselves. That is the
     /// uncomfortable possibility, which is the reason to ask rather than not.
     pub want: Option<String>,
-    /// USERS.md 7, roughly: is this machine a host, a client, or both?
+    /// Roughly: is this machine a host, a client, or both?
     pub role: Option<String>,
-    /// USERS.md 6: cash or credit. Only asked of a machine that could host.
+    /// Cash or credit. Only asked of a machine that could host.
     pub share_for: Option<String>,
-    /// USERS.md 5, in its factual form: current spend, not willingness to pay.
+    /// The factual form of what they pay now: current spend, not willingness
+    /// to pay.
     pub pays_today: Option<String>,
     /// Asked only of a non-Linux machine: is there a Linux box behind it?
     pub other_linux: Option<String>,

apps/nesdoctor/src/sys.rs

@@ -48,8 +48,8 @@ pub struct Gpu {
     pub name: String,
     pub vendor: Option<String>,
     /// The DRM render node, where one exists. Linux only, and a hard
-    /// requirement in `contracts/host-requirements.md`: a card without one
-    /// cannot host, however good it is.
+    /// requirement: a card without one cannot host, however good it is.
+    /// ref(d-0002)
     pub render_node: Option<String>,
 }