docs: Updated to remove Goerli.

[stoobie]

Description of the Changes

Updated to remove Goerli.

Based on this announcement from yesterday, April 2, 2024:

Following the mass exodus of Ethereum Goerli validators and the utter inactivity of Starknet Goerli over the last day, Starknet Goerli testnet will be shutting down later today to avoid maintaining an inactive network. Sepolia testnet awaits with open arms. See you there!

PR Preview URL

Please use the Files changed tab or Reviewable to see what has been removed. I only included links to specific pages where it is easy to view the changes, but the site preview does not show what was changed or removed, only how the site will appear when published.

• Current limits
• Footer:
• Release notes
• Deprecated, unsupported, and removed features
• Starknet contracts and sequencer addresses
• Bridged tokens

Check List

• [x] Changes have been done against main branch, and PR does not conflict
• [x] PR title follows the convention: <docs/feat/fix/chore>(optional scope): <description>, e.g: fix: minor typos in code

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This change is 

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[github-actions[bot]]

Your preview build is ready! ✨ Check the following link in 1-2 minutes: https://starknet-io.github.io/starknet-docs/pr-1212/documentation/ .