chore: hide USAGE.md

This highlight the fact that it's not designed for direct consumption and it no longer needs a special handling in `npmignore`.

scripts/normalize-packages

@@ -124,7 +124,7 @@ require('exec-promise')(() =>
 
     return Promise.all([
       forceRelativeSymlink(NPMIGNORE_PATH, `${dir}/.npmignore`),
-      readFile(`${dir}/USAGE.md`, 'utf8')
+      readFile(`${dir}/.USAGE.md`, 'utf8')
         .then(content =>
           writeFile(
             `${dir}/README.md`,

scripts/npmignore

@@ -29,4 +29,3 @@ __snapshots__/
 
 /docs/
 /src/
-/USAGE.md