Files ending in `.markdown` don't sync properly

[Kanad Gupta]

These lines are wrong:

rdme/src/cmds/docs/single.js

Line 54 in fe24984

 if (filePath.endsWith('.md') === false || !filePath.endsWith('.markdown') === false) { 

rdme/src/cmds/changelogs/single.js

Line 48 in fe24984

 if (filePath.endsWith('.md') === false || !filePath.endsWith('.markdown') === false) { 

We should fix this and add a test to check for these files.