title: error with "package main" flagging red in the main.go folder
body: <p>I have written a <code>main.go</code> program and declared the package at the beginning of the code but it flagging red as shown below:
  <a href="https://i.stack.imgur.com/wGtLq.png" rel="noreferrer"><img src="https://i.stack.imgur.com/wGtLq.png" alt="see the flag on the package main" /></a></p>
  <p>When I hover on the package, it displays the following:</p>
  <pre><code>gopls requires a module at the root of your workspace.
  You can work with multiple modules by opening each one as a workspace folder.
  Improvements to this workflow will be coming soon, and you can learn more here:
  https://github.com/golang/tools/blob/master/gopls/doc/workspace.md.
  </code></pre>
  <p>I'd require help on how I can pass this error. Thanks a lot.</p>