fix(structs): Add 5.3 to structs/README (#652)

hongshaoyang · Shao Yang Hong · web-flow · commit 6bd791f2f44a · 2021-04-20T11:19:24.000+02:00
Co-authored-by: Shao Yang Hong &lt;shaoyang.hong@ninjavan.co&gt;
diff --git a/exercises/structs/README.md b/exercises/structs/README.md
@@ -5,3 +5,4 @@ Rust has three struct types: a classic C struct, a tuple struct, and a unit stru
 #### Book Sections
 
 - [Structures](https://doc.rust-lang.org/book/ch05-01-defining-structs.html)
+- [Method Syntax](https://doc.rust-lang.org/book/ch05-03-method-syntax.html)

Original file line number	Diff line number	Diff line change
`@@ -5,3 +5,4 @@ Rust has three struct types: a classic C struct, a tuple struct, and a unit stru`
`5`	`5`	`#### Book Sections`
`6`	`6`
`7`	`7`	`- [Structures](https://doc.rust-lang.org/book/ch05-01-defining-structs.html)`
	`8`	`+- [Method Syntax](https://doc.rust-lang.org/book/ch05-03-method-syntax.html)`