SpringBoot Replace hard-coded links to Micrometer in documentation

Hi Team,

This PR updates the documentation links to use placeholders for versioning.

Changes

• Changed the Micrometer Tracing documentation URL to {url-micrometer-tracing-docs}.
• Changed the Micrometer main documentation URL to {url-micrometer-docs}.
• Ensured links are version-specific for easier referencing.

Related Issue spring-projects/spring-boot#40916

For this fix to work correctly, the Micrometer and Micrometer Tracing documentation must support URLs with fixed version numbers.

Comment From: mhalbritter

Thanks!