style: Update GitHub references

They've changed their anchor pattern for inline comments.

Signed-off-by: W. Trevor King <[email protected]>

Author: wking

style.md

@@ -88,10 +88,10 @@ Following is a fully populated example (not necessarily for copy/paste use)
 
 [capabilities]: config-linux.md#capabilities
 [class-id]: config-linux.md#network
-[integer-over-hex]: https://github.com/opencontainers/runtime-spec/pull/267#discussion_r48360013
+[integer-over-hex]: https://github.com/opencontainers/runtime-spec/pull/267#r48360013
 [keep-prefix]: https://github.com/opencontainers/runtime-spec/pull/159#issuecomment-138728337
-[no-pointer-for-boolean]: https://github.com/opencontainers/runtime-spec/pull/290#discussion_r50296396
-[no-pointer-for-slices]: https://github.com/opencontainers/runtime-spec/pull/316/files#r50782982
-[optional-pointer]: https://github.com/opencontainers/runtime-spec/pull/233#discussion_r47829711
-[pointer-when-updates-require-changes]: https://github.com/opencontainers/runtime-spec/pull/317/files#r50932706
+[no-pointer-for-boolean]: https://github.com/opencontainers/runtime-spec/pull/290#r50296396
+[no-pointer-for-slices]: https://github.com/opencontainers/runtime-spec/pull/316#r50782982
+[optional-pointer]: https://github.com/opencontainers/runtime-spec/pull/233#r47829711
+[pointer-when-updates-require-changes]: https://github.com/opencontainers/runtime-spec/pull/317#r50932706
 [markdown-headers]: https://help.github.com/articles/basic-writing-and-formatting-syntax/#headings