Make target maintainers more easily pingable

Put them all on the same line with just their GitHub handles to make it
very easy to copy and paste (with ctrl-shift-v!!!) the names.

We have no use for email, so I removed all the emails, we don't care
about people's full names either.

Co-authored-by: Thalia Archibald <thalia@archibald.dev>

Author: Noratrieb

src/doc/rustc/src/platform-support/TEMPLATE.md

@@ -6,7 +6,8 @@ One-sentence description of the target (e.g. CPU, OS)
 
 ## Target maintainers
 
-- Some Person, https://github.com/...
+[@Ghost](https://github.com/Ghost)
+[@octocat](https://github.com/octocat)
 
 ## Requirements
 

src/doc/rustc/src/platform-support/aarch64-nintendo-switch-freestanding.md

@@ -4,10 +4,10 @@
 
 Nintendo Switch with pure-Rust toolchain.
 
-## Designated Developers
+## Target Maintainers
 
-* [@leo60228](https://github.com/leo60228)
-* [@jam1garner](https://github.com/jam1garner)
+[@leo60228](https://github.com/leo60228)
+[@jam1garner](https://github.com/jam1garner)
 
 ## Requirements