lwext4 for RT-Thread V2.0.0-dfsv2

Changes

• Support of DFSv2

Synchronization from upstream:

• fixed commented doxygen syntax mismatch;
• used environment variables in install directory;
• ext4_fs.c has an additional CONFIG_EXTENTS_ENABLE affect. Since this item is not additionally configured, and the default value has no effect on compilation conditions, no code was actually changed.

Note: This release is currently only available for RT-Thread Smart, for RT-Thread please choose another release branch.

lwext4 for RT-Thread V1.1.0

v1.1.0

fix bug https://github.com/RT-Thread/rt-thread/pull/4530

lwext4 for RT-Thread V1.0.0

v1.0.0

Update README.md