docs: note SSLS-EXPORT feature in -ssl-sessions doc

Without a libcurl built with the SSLS-EXPORT feature this command line
option produces:

  curl: option --ssl-sessions: the installed libcurl version does not support this
  curl: try 'curl --help' or 'curl --manual' for more information

Add a note of warning on the -ssl-session docs page to account for this.

Closes #17909

diff --git a/docs/cmdline-opts/ssl-sessions.md b/docs/cmdline-opts/ssl-sessions.md
index 054492b41f3fda5a187c4e9afb9048346f2e4147..bb1e251e732dab78266de2d688dc3673e34a2751 100644 (file)
--- a/docs/cmdline-opts/ssl-sessions.md
+++ b/docs/cmdline-opts/ssl-sessions.md
@@ -33,3 +33,6 @@ The SSL session tickets are stored as base64 encoded text, each ticket on
 its own line. The hostnames are cryptographically salted and hashed. While
 this prevents someone from easily seeing the hosts you contacted, they could
 still check if a specific hostname matches one of the values.
+
+This feature requires that the underlying libcurl was built with the
+experimental SSL session import/export feature (SSLS-EXPORT) enabled.