styleguide: accomidate upstreams without mailing lists

Not all upstream projects have "mailing lists", and sections of the
styleguide which reference linking to the upstream list might be
confusing to developers.

Make it clear that the upstream link can refer to a merge PR as well.

Signed-off-by: Alex Stewart <[email protected]>

Author: amstewart

docs/styleguide.md

@@ -130,9 +130,9 @@ Contributors are free to use a single newline to create logical breaks between d
 At a minimum, you should add an additional message trailer declaring the [upstream status](https://www.openembedded.org/wiki/Commit_Patch_Message_Guidelines#Patch_Header_Recommendations:_Upstream-Status) of the .patch file at the time of your OE commit. These status lines are crucial to helping the project maintainers properly upgrade and rebase recipes. Common status lines are:
 
 * `Upstream-Status: Inappropriate [$rationale]` ([ex](https://github.com/ni/meta-nilrt/blob/nilrt/master/sumo/recipes-support/curl/curl/0005-Add-nicurl-wrapper-functions.patch)) For when the `.patch` change is specific to NI LinuxRT and would not be desired (or has been rejected) by upstream.
-* `Upstream-Status: Not Submitted [$rationale]` ([ex](https://github.com/ni/meta-nilrt/blob/nilrt/master/sumo/recipes-gnome/florence/files/0004-Add-option-for-automatic-bring-to-top.patch)) For when the `.patch` file is being included in NILRT before being submitted to its upstream project. This should only occur if the `.patch` is needed for an immediate NILRT release and there is no time to get it reviewed upstream beforehand. Or if - as in the case of the example - the upstream mailing list is dead.
-* `Upstream-Status: Submitted [$upstream_mailing_list_link]` ([ex](https://github.com/ni/meta-nilrt/blob/1e6453ebca8735de96eaaf3bc931d22998c8dfb3/recipes-support/curl/curl/0014-Fixup-lib1529-test.patch)) For when the `.patch` has been submitted to the upstream project's mailing list, but needs to be pulled into NILRT prior to final upstream approval.
-* `Upstream-Status: Accepted [$upstream_mailing_list_link]` ([ex](https://github.com/ni/meta-nilrt/blob/904bd00bf24d8fe61d3a13b8ece368c9741a73fc/recipes-devtools/opkg/files/0002-libopkg-clear-curl-properties-on-download-error-to-p.patch#L36)) For when the `.patch` has been approved and pulled by the upstream project.
+* `Upstream-Status: Not Submitted [$rationale]` ([ex](https://github.com/ni/meta-nilrt/blob/nilrt/master/sumo/recipes-gnome/florence/files/0004-Add-option-for-automatic-bring-to-top.patch)) For when the `.patch` file is being included in NILRT before being submitted to its upstream project. This should only occur if the `.patch` is needed for an immediate NILRT release and there is no time to get it reviewed upstream beforehand. Or if - as in the case of the example - the upstream repo is dead.
+* `Upstream-Status: Submitted [$upstream_link]` ([ex](https://github.com/ni/meta-nilrt/blob/1e6453ebca8735de96eaaf3bc931d22998c8dfb3/recipes-support/curl/curl/0014-Fixup-lib1529-test.patch)) For when the `.patch` has been submitted to the upstream project by mailing list or merge PR, but needs to be pulled into NILRT prior to final upstream approval.
+* `Upstream-Status: Accepted [$upstream_link]` ([ex](https://github.com/ni/meta-nilrt/blob/904bd00bf24d8fe61d3a13b8ece368c9741a73fc/recipes-devtools/opkg/files/0002-libopkg-clear-curl-properties-on-download-error-to-p.patch#L36)) For when the `.patch` has been approved and pulled by the upstream project.
 
 
 #### .patch file names