Updates the documentation of the modular contracts based on the recent refactor
<!-- start pr-codex -->
---
## PR-Codex overview
The focus of this PR is to update metadata and add GitHub links to modular contract pages.
### Detailed summary
- Added GitHub links to `TransferableERC20`, `TransferableERC721`, `TransferableERC1155`, and `SequentialTokenIdERC1155` contracts
- Updated metadata for contract pages
- Removed unnecessary image imports
- Updated sidebar links for `Get Started` section in the contracts page
> The following files were skipped due to too many changes: `apps/portal/src/app/contracts/sidebar.tsx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-20/misc/creatorTokenERC20/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-1155/metadata/openEditionMetadataERC1155/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-721/metadata/openEditionMetadataERC721/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/core-contracts/erc-721/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-20/minting/mintableERC20/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-721/minting/mintableERC721/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-1155/minting/mintableERC1155/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/core-contracts/erc-20/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/core-contracts/erc-1155/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-1155/metadata/batchMetadataERC1155/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-721/metadata/batchMetadataERC721/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-1155/minting/claimableERC1155/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/get-started/deploy-modular-contract/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-20/minting/claimableERC20/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-721/minting/claimableERC721/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/get-started/create-core-contract/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-721/misc/royaltyERC721/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/module-contracts/erc-1155/misc/royaltyERC1155/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/how-it-works/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/get-started/page.mdx`, `apps/portal/src/app/contracts/modular-contracts/get-started/create-module-contract/page.mdx`
> ✨ Ask PR-Codex anything about this PR by commenting with `/codex {your question}`
<!-- end pr-codex -->