Fix broken links in documentation

[Chaedie]

Description

Fix broken Maven Central links that fail the broken-link checker after releases.

Changed search.maven.org to central.sonatype.com in README and documentation files.

All links updated from:

• Old: https://search.maven.org/artifact/com.pinterest.ktlint/ktlint-cli
• New: https://central.sonatype.com/artifact/com.pinterest.ktlint/ktlint-cli?smo=true

Closes #3184

Checklist

Before submitting the PR, please check following (checks which are not relevant may be ignored):

• Commit message are well written. In addition to a short title, the commit message also explain why a change is made.
• At least one commit message contains a reference Closes #<xxx> or Fixes #<xxx> (replace<xxx> with issue number)
• Tests are added
• KtLint format has been applied on source code itself and violations are fixed
• PR title is short and clear (it is used as description in the release changelog)
• PR description added (background information)

Documentation is updated. See difference between snapshot and release documentation

• Snapshot documentation in case documentation is to be released together with a code change
• Release documentation in case documentation is related to a released version of ktlint and has to be published as soon as the change is merged to master