hive-forge: update --tail field doc to match count-then-page impl (argus on #770)

hive-forge/src/verbs/comments.rs

@@ -36,9 +36,11 @@ pub struct Args {
     /// Mutually exclusive with `--tail`.
     #[arg(long, default_value_t = 50, conflicts_with = "tail")]
     limit: u64,
-    /// Return the last `N` comments in chronological order. Pages
-    /// through every comment on the issue under the hood, then
-    /// slices the tail. Mutually exclusive with `--limit`.
+    /// Return the last `N` comments in chronological order. Reads
+    /// the issue's `comments` count first, then fetches only the
+    /// `ceil(N/50) + 1` pages that contain the tail — work is
+    /// bounded by N, not by thread length. Mutually exclusive with
+    /// `--limit`.
     #[arg(long)]
     tail: Option<usize>,
 }