Merge bitcoin/bitcoin#25090: doc: Explain Bitcoin Core instead of Bitcoin in README.md

faeb5b5 doc: Explain Bitcoin Core in README.md (MacroFake)

Pull request description:

  Currently the README doesn't explain what Bitcoin Core is. Fix that.

  Further reading / Inspired by:

  * bitcoin/bitcoin#25012
  * bitcoin-core/bitcoincore.org#783
  * bitcoin-core/bitcoincore.org#784

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Tree-SHA512: f9a9460853487a46ba0219d26cefa1fcf8d650deb3c2656737a54648016af0cdac58c5d4641a390be8c05f3e78185bd99801e239fcb87d410c4df31f61bc7016

Author: fanquake

README.md

@@ -6,18 +6,14 @@ https://bitcoincore.org
 For an immediately usable, binary version of the Bitcoin Core software, see
 https://bitcoincore.org/en/download/.
 
-Further information about Bitcoin Core is available in the [doc folder](/doc).
-
-What is Bitcoin?
-----------------
+What is Bitcoin Core?
+---------------------
 
-Bitcoin is an experimental digital currency that enables instant payments to
-anyone, anywhere in the world. Bitcoin uses peer-to-peer technology to operate
-with no central authority: managing transactions and issuing money are carried
-out collectively by the network. Bitcoin Core is the name of open source
-software which enables the use of this currency.
+Bitcoin Core connects to the Bitcoin peer-to-peer network to download and fully
+validate blocks and transactions. It also includes a wallet and graphical user
+interface, which can be optionally built.
 
-For more information read the original Bitcoin whitepaper.
+Further information about Bitcoin Core is available in the [doc folder](/doc).
 
 License
 -------