Added rudimentary build steps to readme.
Added rudimentary build steps to readme.

(cherry picked from commit df7e525)

ilinum/intellij-scala,jastice/intellij-scala,jastice/intellij-scala,JetBrains/intellij-scala,triplequote/intellij-scala,JetBrains/intellij-scala,loskutov/intellij-scala,loskutov/intellij-scala,triplequote/intellij-scala,jastice/intellij-scala,ilinum/intellij-scala,jastice/intellij-scala,loskutov/intellij-scala,triplequote/intellij-scala,ilinum/intellij-scala