chore: Updated some of the docs and messages around setting pipefail.

Setting pipefail necessitates other changes away from the default
functioning of ansible, this is made more explicit to the user.

Author: Dylan Morroll

src/ansiblelint/rules/risky_shell_pipe.md

@@ -7,6 +7,9 @@ The return status of a pipeline is the exit status of the command. The
 `pipefail` option ensures that tasks fail as expected if the first command
 fails.
 
+This does not work in the standard (POSIX) shell. You will need to set the executable
+to a different shell, such as bash. See the example below.
+
 As this requirement does not apply to PowerShell, for shell commands that have
 `pwsh` inside `executable` attribute, this rule will not trigger.
 

src/ansiblelint/rules/risky_shell_pipe.py

@@ -15,7 +15,7 @@
 
 
 class ShellWithoutPipefail(AnsibleLintRule):
-    """Shells that use pipes should set the pipefail option."""
+    """Shells that use pipes should set the pipefail option. NB: This requires changing the shell, see the docs."""
 
     id = "risky-shell-pipe"
     description = (
@@ -24,7 +24,8 @@ class ShellWithoutPipefail(AnsibleLintRule):
         "any part of the pipeline other than the terminal command "
         "fails, the whole pipeline will still return 0, which may "
         "be considered a success by Ansible. "
-        "Pipefail is available in the bash shell."
+        "Pipefail is not available in the default (POSIX) shell, "
+        "consider bash."
     )
     severity = "MEDIUM"
     tags = ["command-shell"]