Tronxy P802ma rear frame brace

found the front in the original worked perfect for the p802ma, but the rear needed some work, here is the first edit, will check/test/tweak if needed.

updated version, needed a screw hole and a size tweak for clearance.
10/2/17 corrected issues with some slicers reporting errors or holes

for the install you will need to loosen the back nuts on the threaded rods to let it squeeze into place.