Add exofs.txt to filesystems Documentation index and fix some typos,
identation and grammar.
Signed-off-by: NThadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>

Added some documentation in exofs.txt, as well as a BUGS file.

For further reading, operation instructions, example scripts
and up to date infomation and code please see:
http://open-osd.orgSigned-off-by: NBoaz Harrosh <bharrosh@panasas.com>