[DOCS] Consolidate `routing` parameter definitions (#73107)

Combines duplicate definitions for the `routing` parameter.

docs/reference/indices/add-alias.asciidoc

@@ -67,7 +67,7 @@ include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=timeoutparms]
 (Optional, query object)
 include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=index-alias-filter]
 
-include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=index-routing]
+include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=routing]
 
 [[add-alias-api-example]]
 ==== {api-examples-title}

docs/reference/indices/aliases.asciidoc

@@ -151,7 +151,7 @@ until an additional index is referenced. At that point, there will be no write i
 writes will be rejected.
 ====
 
-include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=index-routing]
+include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=routing]
 +
 See <<aliases-routing>> for an example.
 

docs/reference/rest-api/common-parms.asciidoc

@@ -798,15 +798,9 @@ end::requests_per_second[]
 
 tag::routing[]
 `routing`::
-(Optional, string) Target the specified primary shard.
-end::routing[]
-
-tag::index-routing[]
-`routing`::
 (Optional, string)
-Custom <<mapping-routing-field, routing value>>
-used to route operations to a specific shard.
-end::index-routing[]
+Custom value used to route operations to a specific shard.
+end::routing[]
 
 tag::cat-s[]
 `s`::

docs/reference/search/explain.asciidoc

@@ -77,7 +77,7 @@ include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=search-q]
   (Optional, string) A comma-separated list of stored fields to return in the 
   response.
 
-include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=index-routing]
+include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=routing]
 
 include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=source]