Remove the modification of number of shards from the offline installation

[AlexRuiz7]

Description

In #6946, it was requested to remove the step to tweak the number of shards in the wazuh-template.json for the offline installation. This PR removes such instructions.

We plan to add this back in the future as part of a major update of the wazuh-indexer documentation.

Checks

Docs building

• Compiles without warnings.

Code formatting and web optimization

• Uses three spaces indentation.
• Adds or updates meta descriptions accordingly.
• Updates the redirects.js script if necessary (check this guide).

Writing style

• Uses present tense, active voice, and semi-formal registry.
• Uses short, simple sentences.
• Uses bold for user interface elements, italics for key terms or emphasis, and code font for Bash commands, file names, REST paths, and code.