Add positions info into term_vector doc (#44379)

docs/reference/mapping/params/term-vector.asciidoc

@@ -8,6 +8,8 @@ Term vectors contain information about the terms produced by the
 * the position (or order) of each term.
 * the start and end character offsets mapping the term to its
   origin in the original string.
+* payloads (if they are available) — user-defined binary data
+  associated with each term position.
 
 These term vectors can be stored so that they can be retrieved for a
 particular document.
@@ -20,9 +22,11 @@ The `term_vector` setting accepts:
 `with_positions`::          Terms and positions are stored.
 `with_offsets`::            Terms and character offsets are stored.
 `with_positions_offsets`::  Terms, positions, and character offsets are stored.
+`with_positions_payloads`:: Terms, positions, and payloads are stored.
+`with_positions_offsets_payloads`::  Terms, positions, offsets and payloads are stored.
 
-The fast vector highlighter requires `with_positions_offsets`.  The term
-vectors API can retrieve whatever is stored.
+The fast vector highlighter requires `with_positions_offsets`.
+<<docs-termvectors, The term vectors API>> can retrieve whatever is stored.
 
 WARNING:  Setting `with_positions_offsets` will double the size of a field's
 index.