doc: NODE_EXTRA_CA_CERTS is ignored if setuid root

Fixes: #22081

PR-URL: #23770
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>

Author: bnoordhuis

doc/api/cli.md

@@ -525,6 +525,9 @@ malformed, but any errors are otherwise ignored.
 Note that neither the well known nor extra certificates are used when the `ca`
 options property is explicitly specified for a TLS or HTTPS client or server.
 
+This environment variable is ignored when `node` runs as setuid root or
+has Linux file capabilities set.
+
 ### `NODE_ICU_DATA=file`
 <!-- YAML
 added: v0.11.15

doc/node.1

@@ -302,6 +302,9 @@ If
 is missing or misformatted, a message will be emitted once using
 .Sy process.emitWarning() ,
 but any errors are otherwise ignored.
+.Pp
+This environment variable is ignored when `node` runs as setuid root or
+has Linux file capabilities set.
 .
 .It Ev NODE_ICU_DATA Ar file
 Data path for ICU (Intl object) data.