Rollup merge of rust-lang#79351 - Takashiidobe:keyword-docs-typo, r=m-ou-se

Fix typo in `keyword` docs for traits

This PR fixes a small typo in the `keyword_docs.rs` file, describing the differences between the 2015 and 2018 editions of traits.

Author: Dylan-DPC

library/std/src/keyword_docs.rs

@@ -1739,7 +1739,7 @@ mod super_keyword {}
 ///
 /// # Differences between the 2015 and 2018 editions
 ///
-/// In the 2015 edition parameters pattern where not needed for traits:
+/// In the 2015 edition the parameters pattern was not needed for traits:
 ///
 /// ```rust,edition2015
 /// trait Tr {