Discriminator: Define "schema name" and add clarifications

The `discriminator` keyword uses the concept of "schema names", but what
that means is never defined. There is no concept of a schema having a
name is JSON Schema. They only have URIs.

I also added some clarifications where the use of schema names got
confusing.

Author: jdesrosiers

versions/3.1.1.md

@@ -2701,7 +2701,11 @@ components:
 
 When request bodies or response payloads may be one of a number of different schemas, a `discriminator` object can be used to aid in serialization, deserialization, and validation.  The discriminator is a specific object in a schema which is used to inform the consumer of the document of an alternative schema based on the value associated with it.
 
-When using the discriminator, _inline_ schemas will not be considered.
+`discriminator` uses a schema's "name" to automatically map a property value to
+a schema. The schema's "name" is the property name used when declaring the
+schema as a component. For example, the name of the schema at
+`#/components/schemas/Cat` is "Cat". Therefore, when using `discriminator`,
+_inline_ schemas will not be considered because they don't have a "name".
 
 ##### Fixed Fields
 Field Name | Type | Description
@@ -2763,7 +2767,7 @@ MyResponseType:
       monster: 'https://gigantic-server.com/schemas/Monster/schema.json'
 ```
 
-Here the discriminator _value_ of `dog` will map to the schema `#/components/schemas/Dog`, rather than the default (implicit) value of `Dog`.  If the discriminator _value_ does not match an implicit or explicit mapping, no schema can be determined and validation SHOULD fail. Mapping keys MUST be string values, but tooling MAY convert response values to strings for comparison.
+Here the discriminator _value_ of `dog` will map to the schema `#/components/schemas/Dog`, rather than the default (implicit) `#/components/schemas/dog`.  If the discriminator _value_ does not match an implicit or explicit mapping, no schema can be determined and validation SHOULD fail. Mapping keys MUST be string values, but tooling MAY convert response values to strings for comparison.
 
 When used in conjunction with the `anyOf` construct, the use of the discriminator can avoid ambiguity where multiple schemas may satisfy a single payload.
 
@@ -2820,7 +2824,7 @@ a payload like this:
 }
 ```
 
-will indicate that the `Cat` schema be used.  Likewise this schema:
+will indicate that the `#/components/schemas/Cat` schema be used.  Likewise this payload:
 
 ```json
 {
@@ -2829,7 +2833,7 @@ will indicate that the `Cat` schema be used.  Likewise this schema:
 }
 ```
 
-will map to `Dog` because of the definition in the `mapping` element.
+will map to `#/components/schemas/Dog` because the `dog` entry in the `mapping` element maps to `Dog` which is the schema name for `#/components/schemas/Dog`.
 
 
 #### <a name="xmlObject"></a>XML Object