tor-keymgr: Fix a broken docs link
Fixes:
cargo doc --workspace $f --document-private-items
1 | //! [`KeySpecifier`] implementations for hidden service keys.
| ^^^^^^^^^^^^ no item named `KeySpecifier` in scope
8 | /// A helper for defining service [`KeySpecifier`]s.
| ^^^^^^^^^^^^ no item named `KeySpecifier` in scope
Edited by Ian Jackson