adding contributors to template

adds the list of contributors to the template. the contributors are: enselic, ralfjung, trolldemorted, matthiaskrgr, ttsugriy, kobzol, and lnicola.

this commit updates `example.md` by adding the contributors to the list. the changes can be seen in the diff:

```diff
diff --git a/templates/example.md b/templates/example.md
index a12803718a3e..da0ecc84c0c6 100644
--- a/templates/example.md
+++ b/templates/example.md
@@ -10,3 +10,16 @@
 - [ci: do not hide error logs in a group](rust-lang/rust#114573)
 - [:arrow_up: `rust-analyzer`](rust-lang/rust#114576)
 - [rollup of 9 pull requests](rust-lang/rust#114585)
+
+### contributors
+
+- [enselic](https://github.com/enselic)
+- [enselic](https://github.com/enselic)
+- [ralfjung](https://github.com/ralfjung)
+- [trolldemorted](https://github.com/trolldemorted)
+- [matthiaskrgr](https://github.com/matthiaskrgr)
+- [matthiaskrgr](https://github.com/matthiaskrgr)
+- [ttsugriy](https://github.com/ttsugriy)
+- [kobzol](https://github.com/kobzol)
+- [lnicola](https://github.com/lnicola)
+- [matthiaskrgr](https://github.com/matthiaskrgr)
```

templates/example.md

@@ -10,3 +10,16 @@
 - [CI: do not hide error logs in a group](https://github.com/rust-lang/rust/pull/114573)
 - [:arrow_up: `rust-analyzer`](https://github.com/rust-lang/rust/pull/114576)
 - [Rollup of 9 pull requests](https://github.com/rust-lang/rust/pull/114585)
+
+### Contributors
+
+- [Enselic](https://github.com/Enselic)
+- [Enselic](https://github.com/Enselic)
+- [RalfJung](https://github.com/RalfJung)
+- [Trolldemorted](https://github.com/Trolldemorted)
+- [matthiaskrgr](https://github.com/matthiaskrgr)
+- [matthiaskrgr](https://github.com/matthiaskrgr)
+- [ttsugriy](https://github.com/ttsugriy)
+- [Kobzol](https://github.com/Kobzol)
+- [lnicola](https://github.com/lnicola)
+- [matthiaskrgr](https://github.com/matthiaskrgr)