title: Contentful regex to check if all characters are lowercase
body: <p>I know there a 1,000,000 regex questions but I have one I've been unable to find the answer too</p>
  
  <p>In contentful (a headless CMS software) you can set validations for certain fields</p>
  
  <p><a href="https://i.stack.imgur.com/YY2xR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/YY2xR.png" alt="enter image description here"></a></p>
  
  <p>Now I have set this regex <code>[a-z]+</code> to check if the string provided in this field is all lowercase letters (numbers and symbols are ok), but when I test it out, I am still allowed to use Capital letters.</p>
  
  <p>Is my regex wrong? Or am I entering it wrong in this field??</p>