docs: Updated examples and added note about the fact that the `/` for date rounding in date math index names should be url encoded as `%2F`

docs/reference/api-conventions.asciidoc

@@ -88,13 +88,15 @@ You must enclose date math index name expressions within angle brackets. For exa
 
 [source,js]
 ----------------------------------------------------------------------
-curl -XGET 'localhost:9200/<logstash-{now/d-2d}>/_search' {
+curl -XGET 'localhost:9200/<logstash-{now%2Fd-2d}>/_search' {
   "query" : {
     ...
   }
 }
 ----------------------------------------------------------------------
 
+NOTE: The `/` used for date rounding must be url encoded as `%2F` in any url.
+
 The following example shows different forms of date math index names and the final index names
 they resolve to given the current time is 22rd March 2024 noon utc.
 
@@ -119,7 +121,7 @@ three days, assuming the indices use the default Logstash index name format,
 
 [source,js]
 ----------------------------------------------------------------------
-curl -XGET 'localhost:9200/<logstash-{now/d-2d}>,<logstash-{now/d-1d}>,<logstash-{now/d}>/_search' {
+curl -XGET 'localhost:9200/<logstash-{now%2Fd-2d}>,<logstash-{now%2Fd-1d}>,<logstash-{now%2Fd}>/_search' {
   "query" : {
     ...
   }