[DOC] Consistently reference indices parameter in API key examples (#97174)

This PR adjusts API key examples to consistently use indices instead of index parameter. Technically, both are supported as request parameters, but indices is more aligned with get API key response.

Relates to #97027, where the change was already made for create API key examples.

x-pack/docs/en/rest-api/security/bulk-update-api-keys.asciidoc

@@ -82,7 +82,7 @@ POST /_security/api_key
   "role_descriptors": {
     "role-a": {
       "cluster": ["all"],
-      "index": [
+      "indices": [
         {
           "names": ["index-a*"],
           "privileges": ["read"]
@@ -156,7 +156,7 @@ Further, assume that the owner user's permissions are:
 --------------------------------------------------
 {
   "cluster": ["all"],
-  "index": [
+  "indices": [
     {
       "names": ["*"],
       "privileges": ["all"]
@@ -178,7 +178,7 @@ POST /_security/api_key/_bulk_update
   ],
   "role_descriptors": {
     "role-a": {
-      "index": [
+      "indices": [
         {
           "names": ["*"],
           "privileges": ["write"]
@@ -215,7 +215,7 @@ Both API keys' effective permissions after the update will be the intersection o
 [source,js]
 --------------------------------------------------
 {
-  "index": [
+  "indices": [
     {
       "names": ["*"],
       "privileges": ["write"]
@@ -259,7 +259,7 @@ The API keys' effective permissions after the update will be the same as the own
 --------------------------------------------------
 {
   "cluster": ["all"],
-  "index": [
+  "indices": [
     {
       "names": ["*"],
       "privileges": ["all"]
@@ -275,7 +275,7 @@ For the next example, assume that the owner user's permissions have changed from
 --------------------------------------------------
 {
   "cluster": ["manage_security"],
-  "index": [
+  "indices": [
     {
       "names": ["*"],
       "privileges": ["read"]
@@ -318,7 +318,7 @@ Resulting in the following effective permissions for both API keys:
 --------------------------------------------------
 {
   "cluster": ["manage_security"],
-  "index": [
+  "indices": [
     {
       "names": ["*"],
       "privileges": ["read"]

x-pack/docs/en/rest-api/security/grant-api-keys.asciidoc

@@ -127,7 +127,7 @@ POST /_security/api_key/grant
     "role_descriptors": {
       "role-a": {
         "cluster": ["all"],
-        "index": [
+        "indices": [
           {
           "names": ["index-a*"],
           "privileges": ["read"]
@@ -136,7 +136,7 @@ POST /_security/api_key/grant
       },
       "role-b": {
         "cluster": ["all"],
-        "index": [
+        "indices": [
           {
           "names": ["index-b*"],
           "privileges": ["all"]

x-pack/docs/en/rest-api/security/update-api-key.asciidoc

@@ -87,7 +87,7 @@ POST /_security/api_key
   "role_descriptors": {
     "role-a": {
       "cluster": ["all"],
-      "index": [
+      "indices": [
         {
           "names": ["index-a*"],
           "privileges": ["read"]
@@ -129,7 +129,7 @@ For the examples below, assume that the owner user's permissions are:
 --------------------------------------------------
 {
   "cluster": ["all"],
-  "index": [
+  "indices": [
     {
       "names": ["*"],
       "privileges": ["all"]
@@ -147,7 +147,7 @@ PUT /_security/api_key/VuaCfGcBCdbkQm-e5aOx
 {
   "role_descriptors": {
     "role-a": {
-      "index": [
+      "indices": [
         {
           "names": ["*"],
           "privileges": ["write"]
@@ -181,7 +181,7 @@ The API key's effective permissions after the update will be the intersection of
 [source,js]
 --------------------------------------------------
 {
-  "index": [
+  "indices": [
     {
       "names": ["*"],
       "privileges": ["write"]
@@ -217,7 +217,7 @@ The API key's effective permissions after the update will be the same as the own
 --------------------------------------------------
 {
   "cluster": ["all"],
-  "index": [
+  "indices": [
     {
       "names": ["*"],
       "privileges": ["all"]
@@ -233,7 +233,7 @@ For the next example, assume that the owner user's permissions have changed from
 --------------------------------------------------
 {
   "cluster": ["manage_security"],
-  "index": [
+  "indices": [
     {
       "names": ["*"],
       "privileges": ["read"]
@@ -266,7 +266,7 @@ Resulting in the following effective permissions for the API key:
 --------------------------------------------------
 {
   "cluster": ["manage_security"],
-  "index": [
+  "indices": [
     {
       "names": ["*"],
       "privileges": ["read"]