Revert "Move wiki pages to github pages (#18497)"

This reverts commit 40eb803de1.

docs/_doc/Ethereum-Specification.md

@@ -1,31 +0,0 @@
----
-title: Ethereum specification
----
-Specifications of all ethereum technologies, languages, protocols, etc.
-
-### Whitepapers and design rationale
-
-- [Ethereum Whitepaper](https://github.com/ethereum/wiki/wiki/White-Paper)
-- [Design Rationale](https://github.com/ethereum/wiki/wiki/Design-Rationale)
-- [Ethereum Yellow Paper](http://gavwood.com/Paper.pdf)
-- [ÐΞVp2p Whitepaper](https://github.com/ethereum/wiki/wiki/libp2p-Whitepaper) (WiP)
-- [Ethash](https://github.com/ethereum/wiki/wiki/Ethash)
-
-### Specs
-
-- [JavaScript API](https://github.com/ethereum/wiki/wiki/JavaScript-API#a)
-- [Generic JSON RPC](https://github.com/ethereum/wiki/JSON-RPC)
-- [JSRE admin API](../interface/JavaScript-Console#console-api)
-- [RLP](https://github.com/ethereum/wiki/wiki/RLP)
-- [ÐΞVp2p Wire Protocol](https://github.com/ethereum/wiki/wiki/%C3%90%CE%9EVp2p-Wire-Protocol)
-- [Web3 Secret Storage](https://github.com/ethereum/wiki/wiki/Web3-Secret-Storage-Definition)
-- [Patricia Tree](https://github.com/ethereum/wiki/wiki/Patricia-Tree)
-- [Wire protocol](https://github.com/ethereum/wiki/wiki/Ethereum-Wire-Protocol)
-- [Light client protocol](https://github.com/ethereum/wiki/wiki/Light-client-protocol)
-- [Solidity, Docs & ABI](https://github.com/ethereum/wiki/wiki/Solidity,-Docs-and-ABI)
-- [NatSpec](https://github.com/ethereum/wiki/wiki/Ethereum-Natural-Specification-Format)
-- [Contract ABI](https://github.com/ethereum/wiki/wiki/Ethereum-Contract-ABI)
-- [Ethash](https://github.com/ethereum/wiki/wiki/Ethash)
-- [Ethash C API](https://github.com/ethereum/wiki/wiki/Ethash-C-API)
-- [Ethash DAG](https://github.com/ethereum/wiki/wiki/Ethash-DAG)
-- [ICAP: Inter-exchange Client Address Protocol](https://github.com/ethereum/wiki/wiki/ICAP:-Inter-exchange-Client-Address-Protocol)