docs: clarify intermediate certificate creation instructions

Specifically, explain the v3_ca openssl specification.

Discussion: https://postgr.es/m/20200824175653[email protected]

Backpatch-through: 9.5

diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index e84332cdee6af11d95f15955670a84bd5759039d..6801a1aecce4c0d212b7dd4ca9b2532c51c049ca 100644 (file)
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -2324,8 +2324,10 @@ pg_dumpall -p 5432 | psql -d postgres -p 5433
    The certificates of intermediate certificate authorities
    can also be appended to the file.  Doing this avoids the necessity of
    storing intermediate certificates on clients, assuming the root and
-   intermediate certificates were created with v3_ca
-   extensions.  This allows easier expiration of intermediate certificates.
+   intermediate certificates were created with v3_ca 
+   extensions.  (This sets the certificate's basic constraint of
+   CA to true.)
+   This allows easier expiration of intermediate certificates.