LRDOCS-1031 QAed and wordsmithed Plugins SDK tutorial.
LRDOCS-1031- removed extra text in Next Steps.
Merge branch 'LRDOCS-1031-QA' of https://github.com/mwilliams2014/liferay-docs into pr-176-plugins-sdk
Add next step link to plugins-sdk intro.
LRDOCS-1031 wordsmithed, filled in links, and replaced terminal image.
LRDOCS-1031removed wide terminal image.
LRDOCS-1031 Split the plugins SDK content into two separate tutorials.
Use local URLs
Fix URLs
Merge pull request #943 from jhinkey/pr-176-plugins-sdk

Plugins SDK tutorials