Update NODE_EXTRA_CA_CERTS documentation

Clarified instructions for using NODE_EXTRA_CA_CERTS.

Author: ShawnJackson

docs/pipelines/agents/certificate.md

@@ -141,7 +141,7 @@ console.log(tls.rootCertificates.join("\n"));
 ' > "$ROOT_CERTS_FILE" 
 ```
 
-The `NODE_EXTRA_CA_CERTS` environment variable, introduced in Node v7.3.0, allows you to specify a file that contains one or more CA certificates that Node trusts (in addition to the default bundle). `NODE_EXTRA_CA_CERTS` appends to the trust store. To configure Node.js to trust a certificate:
+The `NODE_EXTRA_CA_CERTS` environment variable, introduced in Node v7.3.0, allows you to specify a file that contains one or more CA certificates that Node trusts (in addition to the default bundle). `NODE_EXTRA_CA_CERTS` appends to the trust store.
 
 1. On your server or CA, export the root (and any intermediate, if needed) certificates as a PEM-encoded file. This format is a text file with `-----BEGIN CERTIFICATE-----` and Base64 data. Make sure that you use Base64-encoded PEM, and not DER. (On Windows, .cer files can be either; you can rename to .pem to avoid confusion. The file can actually have any extension, but .pem or .crt is standard.)