Replace 'build' with 'app'.
Change "build" to "app" in configure doc.

Replace instances of "build" in the text with the word "app."
Merge branch 'development' of https://github.com/thelonelego/mg-game into thelonelego-development
DOCUMENTATION - fix several typos
DOCUMENTATION - rename install, config doc files

Rename files to reflect labeling switch
(replace "build" with "app")