Add link to asciidoctor-diagram-cacoo
Use the block macro style and set the alt text of the image tag
Update sample to add the alt text of the image tag
Add another diagram and diragram titles
Update dependent gem versions and Rakefile to support pdf output and file watch target
Fix indent
Update README for pdf output and file watch mode
Do not ignore *.pdf
Merge branch 'master' into gh-pages

Conflicts:
	.gitignore
	Gemfile
	Gemfile.lock
	Rakefile
	sample.adoc
	sample.html
Resolve merge conflict in .gitignore