[4.5][csv-parser] Documents columnless mode (#43)

content/chapter-parsers/csv-parser/_index.md

@@ -6,6 +6,7 @@ weight: 400
 
 {{< include-headless "chunk/topic-parser-csv-intro.md" >}}
 
+{{< include-headless "chunk/csv-parser-columnless.md" >}}
 
 ## Example: Segmenting hostnames separated with a dash {#example-csv-parser}
 

content/chapter-parsers/csv-parser/reference-parsers-csv/_index.md

@@ -15,7 +15,7 @@ weight:  100
 
 *Description:* Specifies the name of the columns to separate messages to. These names will be automatically available as macros. The values of these macros do not include the delimiters.
 
-
+{{< include-headless "chunk/csv-parser-columnless.md" >}}
 
 ## delimiters() {#csv-parser-delimiter}
 

content/headless/chunk/csv-parser-columnless.md

@@ -0,0 +1,12 @@
+Starting with {{% param "product.abbrev" %}} version 4.5, you can omit the `columns()` option, and extract the values into matches (`$1`, `$2`, `$3`, and so on), which are available as the anonymous list `$*`. For example:
+
+```sh
+@version: current
+
+log {
+    source { tcp(port(2000) flags(no-parse)); };
+
+    parser { csv-parser(delimiters(',') dialect(escape-backslash)); };
+    destination { stdout(template("$ISODATE $*\n")); };
+};
+```