Rollup merge of #49463 - tinaun:patch-2, r=alexcrichton

Don't mention unstable constructors in release notes

Author: kennytm

RELEASES.md

@@ -47,8 +47,6 @@ eg. `static MINUTE: Duration = Duration::from_secs(60);`
 - [`Duration::new`][47300]
 - [`Duration::from_secs`][47300]
 - [`Duration::from_millis`][47300]
-- [`Duration::from_micros`][47300]
-- [`Duration::from_nanos`][47300]
 
 Cargo
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