Add documentation for Bash requirement

This commit adds a note to the docs regarding the requirements for Bash.

Relates elastic#23464

docs/reference/setup/install/zip-targz.asciidoc

@@ -81,6 +81,11 @@ Elasticsearch can be started from the command line as follows:
 By default, Elasticsearch runs in the foreground, prints its logs to the
 standard output (`stdout`), and can be stopped by pressing `Ctrl-C`.
 
+NOTE: All scripts packaged with Elasticsearch require a version of Bash
+that supports arrays and assume that Bash is available at `/bin/bash`.
+As such, Bash should be available at this path either directly or via a
+symbolic link.
+
 include::check-running.asciidoc[]
 
 Log printing to `stdout` can be disabled using the `-q` or `--quiet`