docs: fix how-to audience label from maintainers to contributors

The guides in this section cover active improvement work (updating
devcontainers, toolchains, CI secrets), not operational upkeep by a
dedicated maintainer team.

Author: AlexanderLanin

docs/index.md

@@ -83,7 +83,7 @@ Have a specific task to accomplish? Pick a recipe. Each guide solves one concret
 - [Code Quality](how-to/code-quality.md) — Pre-commit, lint policies, copyright headers
 - [Publishing Modules](how-to/publishing.md) — Release, registry import, consumer access
 
-**For infrastructure maintainers:**
+**For infrastructure contributors:**
 
 - [Writing Documentation](how-to/writing-docs.md) — Sphinx/MyST setup, local preview, status markers
 - [Update the Devcontainer](how-to/update-devcontainer.md) — Build, publish, and roll out a new shared image