v1.0: rename dump commands

[maryamsulemani97]

Rename:

• dumps-dir to dump-dir
• --dumps-dir to --dump-dir
• MEILI_DUMPS_DIR to MEILI_DUMP_DIR

To do

Some may be missing

• Update /learn/configuration/instance_options.md
  • Rename headings
• Update learn/advanced/dumps.md

Reference

• Spec: Rename dump command from --dumps-dir to --dump-dir specifications#204
• Issue on core: CLI stabilization: rename the dumps commands meilisearch#3132
• SME: @dureuill

[dureuill]

Hello @maryamsulemani97 👋

we also convened to rename the Dumps destination section from the online documentation to Dump Directory for consistency with the implementation

(I'm not 100% this belongs to this issue but this appears related so I post here)

I have this PR open to update the link on the implementation side once the documentation is ready.