[PATCH] web: adding section to explain recheck rebase option

[Patrick Robb <probb@iol.unh.edu>]

The UNH-IOL Community Lab now supports an option
to re-apply a patch series for a recheck request
to a specific branch before starting the retests.
This commit updates the dpdk testing page,
adding an explanation of the rebase option
and how it compares to the basic recheck function,
and provides a new example usage for rebase.

Signed-off-by: Patrick Robb <probb@iol.unh.edu>
---
 content/testing/_index.md | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/content/testing/_index.md b/content/testing/_index.md
index 7e17d97..31b464c 100644
--- a/content/testing/_index.md
+++ b/content/testing/_index.md
@@ -113,6 +113,8 @@ do not yet support this feature.
 
 If CI reports a failure for a test label on Patchwork,
 it is possible to request a retest of a patch or series on those label(s).
+The default behavior is that your DPDK patch will be retested "as-is,"
+i.e. your series is not re-applied before testing.
 For a list of Patchwork testing labels, send an email reply on the patch or cover letter like so:
 ```
 Recheck-request: iol-compile-amd64-testing, iol-broadcom-Performance, iol-unit-arm64-testing, github-robot
@@ -120,8 +122,20 @@ Recheck-request: iol-compile-amd64-testing, iol-broadcom-Performance, iol-unit-a
 
 Note that you may omit any labels which are not failing.
 
-This is currently supported by the UNH-IOL Community Lab, and the GitHub Actions robot,
+You may also specify that your series must be re-applied to a given branch before running testing.
+This is useful in a variety of situations, such as when
+your patch originally got applied to a branch which was in a bad state,
+or when the CI testing systems apply your patch to the wrong branch.
+
+In order to select the "re-apply" option, use the rebase={branch_name} option
+when sending your recheck email. An example usage is provided below:
+```
+Recheck-request: rebase=main, iol-intel-Functional, iol-intel-Performance
+```
+
+Rechecks are currently supported by the UNH-IOL Community Lab, and the GitHub Actions robot,
 so just those Patchwork testing labels beginning wih "iol-" or "github-robot".
+IOL is the only lab supporting the re-apply (rebase) option.
 
 ### Mainline Monitoring
 
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2.46.1