doc: fix X509 CA acronym capitalization

PR-URL: nodejs#41841
Reviewed-By: Mestery <[email protected]>
Reviewed-By: Mohammed Keyvanzadeh <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Rich Trott <[email protected]>

Author: tniessen

doc/api/crypto.md

@@ -2464,7 +2464,7 @@ added: v15.6.0
 added: v15.6.0
 -->
 
-* Type: {boolean} Will be `true` if this is a Certificate Authority (ca)
+* Type: {boolean} Will be `true` if this is a Certificate Authority (CA)
   certificate.
 
 ### `x509.checkEmail(email[, options])`