fix: remove override import when ejecting (close #56)

bin/vuepress.js

@@ -42,10 +42,15 @@ program
   .command('eject [targetDir]')
   .description('copy the default theme into .vuepress/theme for customization.')
   .action(async (dir = '.') => {
-    const { copy } = require('fs-extra')
+    const fs = require('fs-extra')
     const source = path.resolve(__dirname, '../lib/default-theme')
     const target = path.resolve(dir, '.vuepress/theme')
-    await copy(source, target)
+    await fs.copy(source, target)
+    // remove the import to default theme override
+    const styleConfig = path.resolve(target, 'styles/config.styl')
+    const content = await fs.readFile(styleConfig, 'utf-8')
+    const transformed = content.split('\n').slice(0, -2).join('\n')
+    await fs.writeFile(styleConfig, transformed)
     console.log(`Copied default theme into ${chalk.cyan(target)}.`)
   })