Increase proposal to 2 releases

README.md

@@ -89,16 +89,16 @@ Rust programs to still compile, but will generate compiler warnings. This gives
 downstream crates time to migrate to non deprecated APIs prior to their removal.
 
 All deprecated APIs are marked using the `#[deprecated]` attribute with both the
-first version they were deprecated in, as well as what new API to use instead.
+first version they were deprecated in, and what new API to use instead.
 
 ```rust
 #[deprecated(since = "51.0.0", note = "Use `date_part` instead")]
 ```
 
-Deprecated APIs will be kept for at least one major release after they were
+Deprecated APIs will be kept for at least two major releases after they were
 deprecated. For example, an API deprecated in `51.3.0` will not be removed until
-at least `53.0.0`. Given the planned release schedule, this is typically between
-3 and 6 months.
+at least `54.0.0`. Given the planned release schedule, this is typically between
+6 and 9 months.
 
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