fix broken internal links

content/cloud/advanced-features/index.md

content/cloud/best-practices/index.md

content/cloud/cli/index.md

content/cloud/faq/index.md

content/cloud/network/index.md

content/cloud/news/index.md

content/cloud/putty/index.md

content/cloud/quick-start/index.md

content/cloud/register/index.md

content/cloud/tools/index.md