Merge bitcoin/bitcoin#29230: doc: update -loglevel help to add `info` to the always logged levels

ec779a2b8e4fcc00596ee8833be35ae9b326552c doc: add unconditional info loglevel following merge of PR 28318 (Jon Atack)

Pull request description:

  Commit ab34dc6012351e7b8aab871dd9d2b38ade1cd9b of #28318 was an incomplete version of [`118c756` (#25203)](https://github.com/bitcoin/bitcoin/pull/25203/commits/118c7567f62df2b882877590f232242d7c627a05) from the `Severity-based logging` parent PR.

  Add the missing text to update the `-loglevel` help doc.

  While here, make the help text a little easier to understand.

  Can be tested by running:

  ```
  ./src/bitcoind -regtest -help-debug | grep -A12 loglevel=
  ```

  before
  ```
    -loglevel=<level>|<category>:<level>
         Set the global or per-category severity level for logging categories
         enabled with the -debug configuration option or the logging RPC:
         info, debug, trace (default=debug); warning and error levels are
         always logged.
  ```

  after
  ```
    -loglevel=<level>|<category>:<level>
         Set the global or per-category severity level for logging categories
         enabled with the -debug configuration option or the logging RPC.
         Possible values are info, debug, trace (default=debug). The
         following levels are always logged: error, warning, info.
  ```

ACKs for top commit:
  stickies-v:
    ACK ec779a2b8e4fcc00596ee8833be35ae9b326552c

Tree-SHA512: 0c375e30a5a4c168ca7d97720e8c287f598216767afedae329824e09a480830faf8537b792c5c4bb647c68681c287fe3005c62093708ce85624e9a71c8245e42

0 files changed, 0 insertions, 0 deletions