reword changelog and re-generate patch

- patches should be in `git format-patch` format and have a
  "cherry picked from" line that refers to the respective upstream
  patch. This way the patch contains meta data like the commit
  message and a reference to the upstream commit ID.

- the change log referred to the commit ID from master branch, when
  it should refer to the batch from nm-1-26 branch (which is upstream
  for 1.26.2, which is currently packaged).

- the change log seem line seems too long. Reword. Also, the main
  purpose of the change is to fix the build (not to backport a patch).

0001-nm-fix-generated-xml-docs-syntax.patch

@@ -1,8 +1,26 @@
+From e2e655cdc588457ede0e1bec070d85d531ad6bdd Mon Sep 17 00:00:00 2001
+From: Valentin David <valentin.david@codethink.co.uk>
+Date: Tue, 8 Sep 2020 17:15:30 +0200
+Subject: [PATCH 1/1] build/docs: fix generated XML syntax in
+ tools/generate-docs-nm-settings-docs-gir.py
+
+Class description may contains double quotes which is not valid as XML
+attribute value.
+
+[thaller@redhat.com: adjust original patch to reformat code with python black]
+
+https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/620
+(cherry picked from commit 54e25f23f53af889703dfc50d51a8afeeea8a439)
+(cherry picked from commit 7d26773138dd4270c45e131761d4e6be58f64d12)
+---
+ tools/generate-docs-nm-settings-docs-gir.py | 8 ++++++--
+ 1 file changed, 6 insertions(+), 2 deletions(-)
+
 diff --git a/tools/generate-docs-nm-settings-docs-gir.py b/tools/generate-docs-nm-settings-docs-gir.py
-index ebda99560a..317b32972a 100755
+index ebda99560a70..317b32972a46 100755
 --- a/tools/generate-docs-nm-settings-docs-gir.py
 +++ b/tools/generate-docs-nm-settings-docs-gir.py
-@@ -244,8 +244,12 @@ def usage():
+@@ -244,8 +244,12 @@ for settingxml in settings:
              "%s needs a gtk-doc block with one-line description" % setting.props.name
          )
      outfile.write(
@@ -17,3 +35,6 @@ index ebda99560a..317b32972a 100755
      )
  
      setting_properties = {
+-- 
+2.26.2
+

NetworkManager.spec

@@ -1097,7 +1097,7 @@ fi
 
 %changelog
 * Sat Sep 19 2020 Yaroslav Fedevych <yaroslav@fedevych.name> - 1:1.26.2-2
-- backport commit 54e25f23f53af889703dfc50d51a8afeeea8a439 which fixes building the package by producing well-formed XML documentation
+- fix build failure due to generating invalid XML documentation
 
 * Wed Aug 19 2020 Thomas Haller <thaller@redhat.com> - 1:1.26.2-1
 - update to 1.26.2