[docs] Link to 0.8 release notes

Makes progress on #671, #1295

Author: joshlf

README.md

@@ -21,12 +21,12 @@ style="color:red;">compile error</span>. Pick two.</span>***
 Zerocopy makes zero-cost memory manipulation effortless. We write `unsafe`
 so you don't have to.
 
-*Thanks for your interest in zerocopy's 0.8 alpha release! For an overview
-of what changes from 0.7, check out our [draft release
-notes][release-notes].*
+*Thanks for using zerocopy 0.8! For an overview of what changes from 0.7,
+check out our [release notes][release-notes], which include a step-by-step
+guide for upgrading from 0.7.*
 
 [customer-request-issue]: https://github.com/google/zerocopy/issues/new/choose
-[release-notes]: https://github.com/google/zerocopy/discussions/1288
+[release-notes]: https://github.com/google/zerocopy/discussions/1680
 
 ## Overview
 

src/lib.rs

@@ -21,12 +21,12 @@
 //! Zerocopy makes zero-cost memory manipulation effortless. We write `unsafe`
 //! so you don't have to.
 //!
-//! *Thanks for your interest in zerocopy's 0.8 alpha release! For an overview
-//! of what changes from 0.7, check out our [draft release
-//! notes][release-notes].*
+//! *Thanks for using zerocopy 0.8! For an overview of what changes from 0.7,
+//! check out our [release notes][release-notes], which include a step-by-step
+//! guide for upgrading from 0.7.*
 //!
 //! [customer-request-issue]: https://github.com/google/zerocopy/issues/new/choose
-//! [release-notes]: https://github.com/google/zerocopy/discussions/1288
+//! [release-notes]: https://github.com/google/zerocopy/discussions/1680
 //!
 //! # Overview
 //!