Formatted README and step0
Changed headline style of README.md
Added a link to the next step
Added image to step1
Added image to step2
Added image to step3
Removed unnecessary original text from step3
Fixed typo
Added image to step4
Added links to step4
Added images to step5
Added images to step6
Added images and links to step7
Added link to step8
Merge pull request #19 from yukiawano/format

Added links and images