Fix a few old links in README (#4686)

README.md

@@ -21,15 +21,15 @@ introduction video is available [here](https://www.youtube.com/watch?v=NUUFhvd7u
 
 Massa's purpose is to make it easy to deploy fully decentralized applications. We've developed two key technologies that
 are exclusive to Massa to help make this possible:
-[autonomous smart contracts](https://docs.massa.net/en/latest/general-doc/autonomous-sc.html) and native
-[front-end hosting](https://docs.massa.net/en/latest/general-doc/decentralized-web.html).
+[autonomous smart contracts](https://docs.massa.net/docs/learn/asc/intro) and native
+[front-end hosting](https://docs.massa.net/docs/learn/decentralized-web).
 
 Here is a list of tools to easily build applications on the Massa blockchain:
 
 - [JS Client library](https://github.com/massalabs/massa-web3) to connect to the Massa blockchain from your applications.
 - [AssemblyScript](https://github.com/massalabs/massa-as-sdk) SDKs to write smart contracts.
 - [Examples of applications](https://github.com/massalabs/massa-sc-examples) built on Massa.
-- [Explorer](https://test.massa.net).
+- [Explorer](https://explorer.massa.net/mainnet).
 - [Interactive API specification](https://playground.open-rpc.org/?schemaUrl=https://test.massa.net/api/v2&uiSchema\[appBar\]\[ui:input\]=false&uiSchema\[appBar\]\[ui:inputPlaceholder\]=Enter+Massa+JSON-RPC+server+URL&uiSchema\[appBar\]\[ui:logoUrl\]=https://massa.net/favicons/favicon.ico&uiSchema\[appBar\]\[ui:splitView\]=false&uiSchema\[appBar\]\[ui:darkMode\]=false&uiSchema\[appBar\]\[ui:title\]=Massa&uiSchema\[appBar\]\[ui:examplesDropdown\]=false&uiSchema\[methods\]\[ui:defaultExpanded\]=false&uiSchema\[methods\]\[ui:methodPlugins\]=true&uiSchema\[params\]\[ui:defaultExpanded\]=false).
 - [Lots of documentation](https://docs.massa.net), from [web3 development](https://docs.massa.net/docs/build/home)
   to [Massa's architecture](https://docs.massa.net/docs/learn/home).