INSTALL-CMAKE.md: document `H2O` config variable

Follow-up to e78b1b3eccfa6a2e367a1225ea1b66dafcdac3c4 #21153

Closes #21769

diff --git a/docs/INSTALL-CMAKE.md b/docs/INSTALL-CMAKE.md
index e6b52a17ee57129496e943a56bc96c37bdd7a5e8..bfc1e451f2b76bbab4ac796f4cec5dbd62d7d07d 100644 (file)
--- a/docs/INSTALL-CMAKE.md
+++ b/docs/INSTALL-CMAKE.md
@@ -482,6 +482,7 @@ Examples:
 
 - `APXS`:                                   Absolute path. Default: search for `apxs`
 - `CADDY`:                                  Absolute path. Default: search for `caddy`
+- `H2O`:                                    Absolute path. Default: search for `h2o`
 - `HTTPD_NGHTTPX`:                          Absolute path. Default: search for `nghttpx`
 - `HTTPD`:                                  Absolute path. Default: search for `apache2`
 - `DANTED`:                                 Absolute path. Default: search for `danted`