smile13241324 c3c2970a50 Fix broken links to missing README files in layers list to fix #8291

Some of the layers do not supply a README.org file which caused
invalid links in the layer list. To avoid this I have changed
spacemacs//generate-layers-from-path to only add links to layers
with a valid README.org file.

I have also removed an invalid check to exclude the non existing directory
"distribution" from the layers list. I think that originally the folder
"distributions" should have been excluded but this is not longer
a feasible action as there is at least one layer with a valid README.org
file in there today. So now we add links to all layers providing a
README.org file independent of their category.

2017-04-17 17:58:02 -04:00