Merge bitcoin/bitcoin#26520: doc: test: update/fix TestShell example instructions

31d0067 doc: test: update/fix TestShell example instructions (Sebastian Falbesoner)

Pull request description:

  This PR tackles two issues in the TestShell documentation:
  - add missing instruction for creating a wallet prior to the `getnewaddress` call (needed as there is no default wallet created anymore since v0.21)
  - fix `generatetoaddress` call syntax (the scripted-diff in commit fa0b916 only worked for tests using `BitcoinTestFramework`)

ACKs for top commit:
  fanquake:
    ACK 31d0067 - current instructions don't work. These do.

Tree-SHA512: d2b7808a06892ad16728cb2b6d4a72b255ad711d27fe98b1de562f80444e7bb25d73296abdde4308162fe3be702864e2f7b7dbbbb000fe54c709951c09e6c730

Author: fanquake

test/functional/test-shell.md

@@ -93,8 +93,10 @@ We now let the first node generate 101 regtest blocks, and direct the coinbase
 rewards to a wallet address owned by the mining node.
 
 ```
+>>> test.nodes[0].createwallet('default')
+{'name': 'default', 'warning': 'Empty string given as passphrase, wallet will not be encrypted.'}
 >>> address = test.nodes[0].getnewaddress()
->>> test.self.generatetoaddress(nodes[0], 101, address)
+>>> test.generatetoaddress(test.nodes[0], 101, address)
 ['2b98dd0044aae6f1cca7f88a0acf366a4bfe053c7f7b00da3c0d115f03d67efb', ...
 ```
 Since the two nodes are both initialized by default to establish an outbound