SPXD-11 | release v0.3.0: update release content
SPXD-11 | release v0.3.0: update README
SPXD-11 | release v0.3.0: fix the wrong markdown link syntaxt
SPXD-11 | release v0.3.0: add Migration section to CHANGELOG, remove .DS_Store, update 404.html
SPXD-11 | release v0.3.0: merge v0.3.0 into develop branch