[DOCS] Reformat cat count API (#45160)

docs/reference/cat/count.asciidoc

@@ -1,41 +1,88 @@
 [[cat-count]]
 === cat count
 
-`count` provides quick access to the document count of the entire
-cluster, or individual indices.
+Provides quick access to a document count of individual indices or all indices
+in a cluster.
+
+NOTE: The document count only includes live documents, not deleted documents
+which have not yet been removed by the merge process.
+
+
+[[cat-count-api-request]]
+==== {api-request-title}
+
+`GET /_cat/count/{index}`
+
+
+[[cat-count-api-path-params]]
+==== {api-path-parms-title}
+
+include::{docdir}/rest-api/common-parms.asciidoc[tag=index]
+
+
+[[cat-count-api-query-params]]
+==== {api-query-parms-title}
+
+include::{docdir}/rest-api/common-parms.asciidoc[tag=http-format]
+
+include::{docdir}/rest-api/common-parms.asciidoc[tag=cat-h]
+
+include::{docdir}/rest-api/common-parms.asciidoc[tag=help]
+
+include::{docdir}/rest-api/common-parms.asciidoc[tag=local]
+
+include::{docdir}/rest-api/common-parms.asciidoc[tag=master-timeout]
+
+include::{docdir}/rest-api/common-parms.asciidoc[tag=cat-s]
+
+include::{docdir}/rest-api/common-parms.asciidoc[tag=cat-v]
+
+
+[[cat-count-api-example]]
+==== {api-examples-title}
+
+[[cat-count-api-example-ind]]
+===== Example with an individual index
+
+The following `count` API request retrieves the document count of a single
+index, `twitter`.
 
 [source,js]
 --------------------------------------------------
-GET /_cat/count?v
+GET /_cat/count/twitter?v
 --------------------------------------------------
 // CONSOLE
 // TEST[setup:big_twitter]
-// TEST[s/^/POST test\/test\?refresh\n{"test": "test"}\n/]
 
-Looks like:
+
+The API returns the following response:
 
 [source,txt]
 --------------------------------------------------
 epoch      timestamp count
-1475868259 15:24:19  121
+1475868259 15:24:20  120
 --------------------------------------------------
-// TESTRESPONSE[s/1475868259 15:24:19/\\d+ \\d+:\\d+:\\d+/ non_json]
+// TESTRESPONSE[s/1475868259 15:24:20/\\d+ \\d+:\\d+:\\d+/ non_json]
+
+[[cat-count-api-example-all]]
+===== Example with all indices in a cluster
 
-Or for a single index:
+The following `count` API request retrieves the document count of all indices in
+the cluster.
 
 [source,js]
 --------------------------------------------------
-GET /_cat/count/twitter?v
+GET /_cat/count?v
 --------------------------------------------------
 // CONSOLE
-// TEST[continued]
+// TEST[setup:big_twitter]
+// TEST[s/^/POST test\/test\?refresh\n{"test": "test"}\n/]
+
+The API returns the following response:
 
 [source,txt]
 --------------------------------------------------
 epoch      timestamp count
-1475868259 15:24:20  120
+1475868259 15:24:20  121
 --------------------------------------------------
 // TESTRESPONSE[s/1475868259 15:24:20/\\d+ \\d+:\\d+:\\d+/ non_json]
-
-
-NOTE: The document count indicates the number of live documents and does not include deleted documents which have not yet been cleaned up by the merge process.

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

@@ -22,6 +22,12 @@ https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html[HTTP accept header].
 Valid values include JSON, YAML, etc.
 end::http-format[]
 
+tag::index[]
+`{index}`::
+(Optional, string) Comma-separated list of index names used to limit returned
+information.
+end::index[]
+
 tag::local[]
 `local`::
 (Optional, boolean) If `true`, the request retrieves information from the local