PEP 761: Add additional links to Sigstore docs (#4035)

Author: sethmlarson

peps/pep-0761.rst

@@ -22,11 +22,11 @@ practitioners <https://www.latacora.com/blog/2019/07/16/the-pgp-problem/>`_
 for many years now, with the biggest issue being that there were few
 alternatives for "artifact signing" being proposed or adopted.
 
-Sigstore's design philosophy has focused on the ergonomics of signing and
-verifying and uses short-lived keys with strongly-bound human-readable
-identities via OpenID Connect. Sigstore has both development and adoption
-momentum, seeing adoption by PyPI, NPM, Homebrew, and GitHub, among other
-ecosystems.
+`Sigstore's <https://docs.sigstore.dev>`_ design philosophy has focused on the
+ergonomics of signing and verifying and `uses short-lived keys with
+strongly-bound human-readable identities via OpenID Connect <https://docs.sigstore.dev/#how-sigstore-works>`_.
+Sigstore has both development and adoption momentum, seeing adoption by PyPI,
+NPM, Homebrew, and GitHub, among other ecosystems.
 
 This PEP proposes to move CPython to using Sigstore exclusively for signing
 artifacts through a deprecation and eventual discontinuance of providing PGP