feat: create parser for zksync info

[itsacoyote]

What :computer:

• Create a parser that replaces tags in markdown content with values defined in a _zksync.json file.

Why :hand:

• For very important content, we don't want to copy/past and rewrite things all over the docs.

How it works

Content is structured in a json file under content/_zksync.json. Tags are wrapped in %% and are prefixed with zk_. The path to the value in the json file is represented with underscores instead of a dot.

Let's say we want to put the Mainnet block explorer URL into a page somewhere. It's in the JSON file as mainnet.block_explorer_url. The tag for it will be %%zk_mainnet_block_explorer_url%%.

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit af0866e):

https://zksync-docs-staging-5eb09--pr12-sf-zk-parser-rkaq72j3.web.app

_{(expires Thu, 18 Apr 2024 13:42:37 GMT)}

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[dutterbutter]

@itsacoyote a very awesome improvement for maintainability 🎉