Merge bitcoin/bitcoin#22739: doc: link to managing-wallets from docs README

1ea11e1 doc: link to managing-wallets from doc readme (fanquake)

Pull request description:

  This was forgotten in #22523.

ACKs for top commit:
  achow101:
    ACK 1ea11e1
  jarolrod:
    ACK 1ea11e1

Tree-SHA512: b82664b282cc0fe733b752c011621593df0f846d2188f12dbc5fedb7ffed2bd161293ce2a369ca973926030795b5f7acde7a1cbf5e337042a6f665906069c656

Author: fanquake

doc/README.md

@@ -77,6 +77,7 @@ The Bitcoin repo's [root README](/README.md) contains relevant information on th
 - [Fuzz-testing](fuzzing.md)
 - [I2P Support](i2p.md)
 - [Init Scripts (systemd/upstart/openrc)](init.md)
+- [Managing Wallets](managing-wallets.md)
 - [PSBT support](psbt.md)
 - [Reduce Memory](reduce-memory.md)
 - [Reduce Traffic](reduce-traffic.md)