api/types/registry: remove deprecated AuthConfig.Email field

This field was no longer used since Docker 1.11 (API version 1.23)
through [moby@aee260d] and [engine-api@9a9e468] but kept, and deprecated
in [engine-api@167efc7] with a fix-up in [moby@6cfff7e8803a7].

This patch removes the field so that we don't have to carry it in the
new moby/api module.

[moby@aee260d]: aee260d4eb
[engine-api@9a9e468]: 9a9e468f50
[engine-api@167efc7]: 167efc72bb
[moby@6cfff7e8803a7]: 6cfff7e880

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

api/docs/v1.52.yaml

@@ -81,7 +81,6 @@ info:
     {
       "username": "string",
       "password": "string",
-      "email": "string",
       "serveraddress": "string"
     }
     ```
@@ -2104,12 +2103,6 @@ definitions:
         type: "string"
       password:
         type: "string"
-      email:
-        description: |
-          Email is an optional value associated with the username.
-
-          > **Deprecated**: This field is deprecated since docker 1.11 (API v1.23) and will be removed in a future release.
-        type: "string"
       serveraddress:
         type: "string"
     example:

api/swagger.yaml

@@ -81,7 +81,6 @@ info:
     {
       "username": "string",
       "password": "string",
-      "email": "string",
       "serveraddress": "string"
     }
     ```
@@ -2104,12 +2103,6 @@ definitions:
         type: "string"
       password:
         type: "string"
-      email:
-        description: |
-          Email is an optional value associated with the username.
-
-          > **Deprecated**: This field is deprecated since docker 1.11 (API v1.23) and will be removed in a future release.
-        type: "string"
       serveraddress:
         type: "string"
     example:

api/types/registry/authconfig.go

@@ -24,11 +24,6 @@ type AuthConfig struct {
 	Password string `json:"password,omitempty"`
 	Auth     string `json:"auth,omitempty"`
 
-	// Email is an optional value associated with the username.
-	//
-	// Deprecated: This field is deprecated since docker 1.11 (API v1.23) and will be removed in the next release.
-	Email string `json:"email,omitempty"`
-
 	ServerAddress string `json:"serveraddress,omitempty"`
 
 	// IdentityToken is used to authenticate the user and get