patch 9.1.0396: filetype: jj files are not recognized

Problem:  jj files are not recognized
Solution: recognize '*.jjdescription' files as jj filetype
          (Gregory Anders)

See: https://github.com/martinvonz/jj

closes: #14733

Signed-off-by: Gregory Anders <greg@gpanders.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/.github/MAINTAINERS b/.github/MAINTAINERS
index ac41ed5..36b352f 100644
--- a/.github/MAINTAINERS
+++ b/.github/MAINTAINERS
@@ -161,6 +161,7 @@
 runtime/ftplugin/java.vim		@zzzyxwvut
 runtime/ftplugin/javascript.vim		@dkearns
 runtime/ftplugin/javascriptreact.vim	@dkearns
+runtime/ftplugin/jj.vim			@gpanders
 runtime/ftplugin/json.vim		@dbarnett
 runtime/ftplugin/json5.vim		@dkearns
 runtime/ftplugin/jsonc.vim		@izhakjakov
@@ -406,6 +407,7 @@
 runtime/syntax/jargon.vim		@h3xx
 runtime/syntax/java.vim			@zzzyxwvut
 runtime/syntax/javascript.vim		@fleiner
+runtime/syntax/jj.vim			@gpanders
 runtime/syntax/json.vim		        @vito-c
 runtime/syntax/jsonc.vim		@izhakjakov
 runtime/syntax/julia.vim		@carlobaldassi