Update the default edition for code blocks to 2021

This is important because the example on https://veykril.github.io/tlborm/decl-macros/minutiae/fragment-specifiers.html#pat is failed due to or-patterns only allowed since 2021 edition.
WaffleLapkin · Apr 17, 2022 · 4ee483e · 4ee483e
1 parent f7ef4fa
commit 4ee483e
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/book.toml b/book.toml
@@ -45,3 +45,7 @@ level = 1
 "/decl-macros/syntax/ast.html" = "../../syntax-extensions/ast.html"
 "/decl-macros/syntax/expansion.html" = "../../syntax-extensions/expansion.html"
 "/decl-macros/syntax/source-analysis.html" = "../../syntax-extensions/source-analysis.html"
+
+[rust]
+# see: https://rust-lang.github.io/mdBook/format/configuration/general.html#rust-options
+edition = "2021"