docs(#2671): trim per-verb arg help (repo-create)

Drop the API path from --org and the "Forgejo applies it to the initial
commit" mechanics from --default-branch (kept the user-facing caveat:
only takes effect with --auto-init). Swept the remaining verbs
(attachment-get, pr-reviews, attach, repo-add-collaborator, comment,
clone, pr-cmd router, …) — already user-relevant, no changes needed.

hive-forge/src/verbs/repo_create.rs

@@ -27,12 +27,10 @@ pub struct Args {
     /// Create the repo as private (default: public).
     #[arg(long)]
     private: bool,
-    /// Default branch name (e.g. `main`). Forgejo applies it to the
-    /// initial commit, so it only takes effect alongside `--auto-init`.
+    /// Default branch name (e.g. `main`). Only takes effect with `--auto-init`.
     #[arg(long = "default-branch")]
     default_branch: Option<String>,
-    /// Create under this organisation (`POST /orgs/<org>/repos`) instead
-    /// of the authenticated user's namespace.
+    /// Create under this organisation instead of your own namespace.
     #[arg(long)]
     org: Option<String>,
     /// Seed an initial commit (README) so the repo is non-empty and can