Remove separators that cause numbering jumps

I have removed the "--------------------" separators as they cause a section number to be skipped and hence incorrect section numbering in the left panel TOC.

Take a look at https://rustwasm.github.io/wasm-bindgen/web-sys/index.html left panel, towards the bottom, and you will see that it's jumps from section 3, to 5, to 7 to 9 - which I am assuming is NOT what you wanted.

guide/src/SUMMARY.md

@@ -80,25 +80,19 @@
       - [`start`](./reference/attributes/on-rust-exports/start.md)
       - [`typescript_custom_section`](./reference/attributes/on-rust-exports/typescript_custom_section.md)
 
---------------------------------------------------------------------------------
-
 - [`web-sys`](./web-sys/index.md)
   - [Using `web-sys`](./web-sys/using-web-sys.md)
   - [Cargo Features](./web-sys/cargo-features.md)
   - [Function Overloads](./web-sys/function-overloads.md)
   - [Type Translations](./web-sys/type-translations.md)
   - [Inheritance](./web-sys/inheritance.md)
 
---------------------------------------------------------------------------------
-
 - [Testing with `wasm-bindgen-test`](./wasm-bindgen-test/index.md)
   - [Usage](./wasm-bindgen-test/usage.md)
   - [Writing Asynchronous Tests](./wasm-bindgen-test/asynchronous-tests.md)
   - [Testing in Headless Browsers](./wasm-bindgen-test/browsers.md)
   - [Continuous Integration](./wasm-bindgen-test/continuous-integration.md)
 
---------------------------------------------------------------------------------
-
 - [Contributing to `wasm-bindgen`](./contributing/index.md)
   - [Testing](./contributing/testing.md)
   - [Internal Design](./contributing/design/index.md)