style: remove consecutive blank lines flagged by rumdl

Assisted-by: ClaudeCode:claude-opus-5

Author: henryiii

docs/guides/index.md

@@ -60,6 +60,5 @@ WebAssembly! All checks point to a linked badge in the guide.
 [sp-repo-review]:           https://pypi.org/project/sp-repo-review
 [scientific-python/cookie]: https://github.com/scientific-python/cookie
 
-
 ```{tableofcontents}
 ```

docs/principles/index.md

@@ -10,6 +10,5 @@ suite for your project.
 [Design recommendations]: /principles/design.md
 [Testing recommendations]: /principles/testing.md
 
-
 ```{tableofcontents}
 ```