docs: f2fs: fix typos in f2fs.rst

docs: f2fs: fix typos in f2fs.rst

This patch fixes two minor typos in Documentation/filesystems/f2fs.rst:

- "ramdom" → "random"
- "reenable" → "re-enable"

The changes improve spelling and consistency in the documentation.

These issues were identified using the 'codespell' tool with the
following command:

  $ find Documentation/ -path Documentation/translations -prune -o \
    -name '*.rst' -print | xargs codespell

Signed-off-by: Yuanye Ma <yuanye.ma20@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250618225546.104949-1-yuanye.ma20@gmail.com