docs(README): fix config code snippet (#149)

README.md

@@ -205,14 +205,14 @@ require('package-info').setup()
             outdated = "|  ", -- Icon for outdated dependencies
         },
     },
-    autostart = true -- Whether to autostart when `package.json` is opened
-    hide_up_to_date = false -- It hides up to date versions when displaying virtual text
+    autostart = true, -- Whether to autostart when `package.json` is opened
+    hide_up_to_date = false, -- It hides up to date versions when displaying virtual text
     hide_unstable_versions = false, -- It hides unstable versions from version list e.g next-11.1.3-canary3
     -- Can be `npm`, `yarn`, or `pnpm`. Used for `delete`, `install` etc...
     -- The plugin will try to auto-detect the package manager based on
     -- `yarn.lock` or `package-lock.json`. If none are found it will use the
     -- provided one, if nothing is provided it will use `yarn`
-    package_manager = `yarn`
+    package_manager = 'yarn'
 }
 ```