docs: remove incorrect MSRV note (#2137)

jamen · web-flow · commit 604f389c708c · 2022-05-25T12:31:06.000-04:00
`tracing`'s lib.rs incorrectly states its MSRV; this commit removes it.
diff --git a/tracing/src/lib.rs b/tracing/src/lib.rs
@@ -119,8 +119,6 @@
 //! tracing = "0.1"
 //! ```
 //!
-//! *Compiler support: requires rustc 1.39+*
-//!
 //! ## Recording Spans and Events
 //!
 //! Spans and events are recorded using macros.
