rewording of sections on "contains", "maxContains", "minContains"

- More cross-references added that note the dependence of these keywords on each other
- Confusing paragraph about logical results removed (and it is redundant with other paragraphs)

Author: karenetheridge

jsonschema-core.xml

@@ -2085,7 +2085,8 @@
                             "items", whose behavior is defined in terms of "prefixItems"
                         </t>
                         <t>
-                            "contains", whose behavior is defined in terms of "minContains"
+                            "contains", whose behavior is affected by the presence and value of
+                            "minContains", in the Validation vocabulary
                         </t>
                     </list>
                 </t>
@@ -2339,15 +2340,10 @@
                         </t>
                         <t>
                             An array instance is valid against "contains" if at least one of
-                            its elements is valid against the given schema. The subschema MUST be
-                            applied to every array element even after the first match has
-                            been found, in order to collect annotations for use by other keywords.
-                            This is to ensure that all possible annotations are collected.
-                        </t>
-                        <t>
-                            Logically, the validation result of applying the value subschema to each
-                            item in the array MUST be ORed with "false", resulting in an overall
-                            validation result.
+                            its elements is valid against the given schema,
+                            except when "minContains" is present and has a value of 0, in which
+                            case an array instance MUST be valid against the "contains" keyword,
+                            even if NONE of its elements is valid against the given schema.
                         </t>
                         <t>
                             This keyword produces an annotation value which is an array of
@@ -2356,8 +2352,16 @@
                             the subschema validates successfully when applied to every index of the
                             instance. The annotation MUST be present if the instance array to which
                             this keyword's schema applies is empty.
+                        </t>
+                        <t>
                             This annotation affects the behavior of "unevaluatedItems" in the
-                            Unevaluated vocabulary.
+                            Unevaluated vocabulary, and MAY also be used to implement the
+                            "minContains" and "maxContains" keywords in the Validation vocabulary.
+                        </t>
+                        <t>
+                            The subschema MUST be applied to every array element even after the first
+                            match has been found, in order to collect annotations for use by other
+                            keywords. This is to ensure that all possible annotations are collected.
                         </t>
                     </section>
                 </section>

jsonschema-validation.xml

@@ -442,8 +442,9 @@
                     </t>
                     <t>
                         A value of 0 is allowed, but is only useful for setting a range
-                        of occurrences from 0 to the value of "maxContains".  A value of
-                        0 with no "maxContains" causes "contains" to always pass validation.
+                        of occurrences from 0 to the value of "maxContains". A value of
+                        0 causes "minContains" to always pass validation (but validation can
+                        still fail against a "maxContains" keyword).
                     </t>
                     <t>
                         Omitting this keyword has the same behavior as a value of 1.