Update code guideline for use of && and || preference.

Signed-off-by: crynobone <crynobone@gmail.com>
fixed typo in components/view/usage.md
Merge branch '2.0' into 2.1
Update changelog.

Signed-off-by: crynobone <crynobone@gmail.com>
Update ToC.

Signed-off-by: crynobone <crynobone@gmail.com>
Merge branch '2.0' into 2.1

Signed-off-by: crynobone <crynobone@gmail.com>

Conflicts:
	src/contents.md
Update changelog.

Signed-off-by: crynobone <crynobone@gmail.com>
Merge branch '2.1'
Update changelog.

Signed-off-by: crynobone <crynobone@gmail.com>