docs: document TRIM "comma" syntax

This syntax is supported by the parser, but is non-standard.

_Not_ backpatched to 9.3 in case we change our minds.

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 615462195b4806a715bf36dc58f2da7dabb775d3..b21c433565c72a0cd0ad3fe74d05b4b830e737ab 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1293,6 +1293,25 @@
        Tom
       
 
+      
+       
+        
+         trim
+        
+        trim(leading | trailing
+        | both from
+        string
+        , characters
+        )
+       
+       text
+       
+        Non-standard version of trim()
+       
+       trim(both from 'xTomxx', 'x')
+       Tom
+      
+