feat: Update zksync era sdk introduction page

[Ngozi-Txfusion]

What

• Updated the content of the SDK home page to improve clarity and usability.
• Enhanced the look and feel of the home page with UI design improvements.
• Increased the maximum line length for markdown files from 120 to 300 characters.
• Changed the template source URL from github:matter-labs/docs-nuxt-template#add-husky to github:matter-labs/docs-nuxt-template to fix the 404 error. ERROR Failed to download https://api.github.com/repos/matter-labs/docs-nuxt-template/tarball/add-husky: 404 Not Found at download (node_modules/giget/dist/index.mjs:31:11) at process.processTicksAndRejections (node:internal/process/task_queues:95:5) at async downloadTemplate (node_modules/giget/dist/index.mjs:302:5) at async resolveConfig (node_modules/c12/dist/index.mjs:288:20) at async extendConfig (node_modules/c12/dist/index.mjs:241:21) at async loadConfig (node_modules/c12/dist/index.mjs:176:5) at async loadNuxtConfig (node_modules/@nuxt/kit/dist/index.mjs:2516:18) at async loadNuxt (node_modules/nuxt/dist/index.mjs:4284:19) at async loadNuxt (node_modules/@nuxt/kit/dist/index.mjs:2570:19) at async Object.run (node_modules/nuxi/dist/chunks/prepare.mjs:53:18) at async runCommand$1 (node_modules/nuxi/dist/shared/nuxi.9edf0930.mjs:1648:16) at async runCommand$1 (node_modules/nuxi/dist/shared/nuxi.9edf0930.mjs:1639:11) at async runMain$1 (node_modules/nuxi/dist/shared/nuxi.9edf0930.mjs:1777:7) [7:14:08 AM] ERROR Failed to download https://api.github.com/repos/matter-labs/docs-nuxt-template/tarball/add-husky: 404 Not Found error: postinstall script from "zksync-docs" exited with 1

Why

These changes were made to provide a better user experience, fix broken links, and ensure the code adheres to the latest standards and practices.

Additionally:

• Due to the enforced line length, I couldn't send a GitHub commit, which resulted from the markdown linting.
• 'bun install' couldn't start because the '#add-husky' branch/tag was not found, so the URL was updated to point to the correct branch."

Image

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit bf4a3d1):

https://zksync-sdk-docs-staging--pr28-update-zksync-era-sd-zpxxj3n2.web.app

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