Rename rippled to xrpld (rippled #6098 and #6347)

[rachelflynn]

Replace any references of rippled.cfg with xrpld.cfg (XRPLF/rippled#6098) and rename the default config directory from ripple to xrpld (XRPLF/rippled#6347), both part of 3.2.0.

The same upstream change (#6098) also renamed the example config file, so this PR additionally renames rippled-example.cfg → xrpld-example.cfg to match. #6347 renames the system name from ripple to xrpld, which changes the default config directory (e.g. $HOME/.config/ripple/ → $HOME/.config/xrpld/). The rippled name will be changed in a separate PR.

Changes

English docs (docs/)

• Changed rippled.cfg → xrpld.cfg and rippled-example.cfg → xrpld-example.cfg
• Renamed the config directory ripple → xrpld in XDG/home paths (e.g. $HOME/.config/xrpld/xrpld.cfg); left package paths (/etc/opt/ripple/, /var/lib/rippled) unchanged
• Added a note to the Conf File Location snippet about the renaming and backwards compatibility
• Fixed a pre-existing typo in Commandline Usage

Translations (@l10n/ja, @l10n/es-ES)

• Renamed the same config filename strings in the corresponding Japanese and Spanish docs
• Renamed the config directory ripple → xrpld in the Japanese docs (the Spanish docs had no such paths)
• Did not update translated prose