Fix typo and spell out auto renewal 30 days before expiration

Author: RebeccaTamachiro

src/content/partials/ssl/universal-ssl-validity.mdx

@@ -3,6 +3,8 @@
 
 ---
 
-For Universal certificates, Cloudflare controls the validity periods and certificate autorities (CAs), making sure that renewal always occur.
+For Universal certificates, Cloudflare controls the validity periods and certificate authorities (CAs), making sure that renewal always occur.
 
-Universal certificates issued by Let's Encrypt, Google Trust Services, or SSL.com have a 90-day validity period. Cloudflare no longer uses DigiCert for newly issued Universal certificates and, for existing ones, the validity period is being adjusted from one year to 90 days.
+Universal certificates issued by Let's Encrypt, Google Trust Services, or SSL.com have a 90-day validity period. Cloudflare no longer uses DigiCert for newly issued Universal certificates and, for existing ones, the validity period is being adjusted from one year to 90 days.
+
+For 90-days certificates, the auto renewal period starts 30 days before expiration.