Add meta titles, descriptions & sidebar labels to all pages

[fmercadop]

Summary

• Added unique, length-optimized meta titles (50–60 chars) and descriptions (120–160 chars) to all 128 doc pages, 2 custom pages, and the homepage
• Shortened the site-wide title from "Welcome to the Datacoves Documentation" to "Datacoves" so every SERP title renders as {page title} | Datacoves within Google's display limit
• Added sidebar_label to every doc page to keep the left navigation concise despite longer SEO titles
• Replaced the Docusaurus placeholder homepage description with intentional copy

What changed

Area	Pages
Homepage + config	2 files (docusaurus.config.js, src/pages/index.js)
Custom pages	2 (contact-us.md, sla.md)
Getting Started	11
Best Practices	12
How-tos	72
Reference	29
Tutorials	2

Scope

Only front-matter fields (title:, description:, sidebar_label:) were modified. No body content, headings, or code changes beyond the Step 0 config/homepage edits.