Fix links on kotlin docs and fix service request context propagation example

[Dogacel]

Motivation:

Some links I tried to click were broken.

Modifications:

• Fix links to the examples.
• Add See also links for kotlin-grpc related stuff.

[github-actions[bot]]

🔍 Build Scan® (commit: 79e807351811afd04682c092c692923bde30467b)

Job name	Status	Build Scan®
build-windows-latest-jdk-19	✅	https://ge.armeria.dev/s/n65obswb5d6ve
build-self-hosted-unsafe-jdk-8	✅	https://ge.armeria.dev/s/dc5m3fxhairtw
build-self-hosted-unsafe-jdk-19-snapshot-blockhound	✅	https://ge.armeria.dev/s/pwnhcytfxrsso
build-self-hosted-unsafe-jdk-17-min-java-17-coverage	✅	https://ge.armeria.dev/s/tkezabcroivls
build-self-hosted-unsafe-jdk-17-min-java-11	✅	https://ge.armeria.dev/s/sbmoa2xmgdcxq
build-self-hosted-unsafe-jdk-17-leak	✅	https://ge.armeria.dev/s/fa7ighshts5zw
build-self-hosted-unsafe-jdk-11	✅	https://ge.armeria.dev/s/m7f7ovet7ktpa
build-macos-12-jdk-19	✅	https://ge.armeria.dev/s/gsrplrj7lsfzc

[minwoox]

@Dogacel 👍 👍 👍