policy-reference: update EBNF to include "every" and "some x in ..."

Fixes open-policy-agent#4216.

Signed-off-by: Stephan Renatus <stephan.renatus@gmail.com>

docs/content/policy-reference.md

@@ -1163,10 +1163,11 @@ rule-body       = [ "else" [ "=" term ] ] "{" query "}"
 query           = literal { ( ";" | ( [CR] LF ) ) literal }
 literal         = ( some-decl | expr | "not" expr ) { with-modifier }
 with-modifier   = "with" term "as" term
-some-decl       = "some" var { "," var }
-expr            = term | expr-call | expr-infix
-expr-call       = var [ "." var ] "(" [ term { "," term } ] ")"
-expr-infix      = [ term "=" ] term infix-operator term
+some-decl       = "some" term { "," term } { "in" expr }
+expr            = term | expr-call | expr-infix | expr-every
+expr-call       = var [ "." var ] "(" [ expr { "," expr } ] ")"
+expr-infix      = [ term "=" ] expr infix-operator expr
+expr-every      = "every" var { "," var } "in" ( term | expr-call | expr-infix ) "{" query "}"
 term            = ref | var | scalar | array | object | set | array-compr | object-compr | set-compr
 array-compr     = "[" term "|" rule-body "]"
 set-compr       = "{" term "|" rule-body "}"