patch 9.1.0986: filetype: 'jj' filetype is a bit imprecise

Problem:  filetype: 'jj' filetype is a bit imprecise
Solution: rename 'jj' filetype to 'jjdescription'
          (Gregory Anders)

closes: #16364

Signed-off-by: Gregory Anders <greg@gpanders.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/filetype.vim b/runtime/filetype.vim
index 1adb403..4d7205f 100644
--- a/runtime/filetype.vim
+++ b/runtime/filetype.vim
@@ -1244,7 +1244,7 @@
 au BufNewFile,BufRead *.jinja			setf jinja
 
 " Jujutsu
-au BufNewFile,BufRead *.jjdescription		setf jj
+au BufNewFile,BufRead *.jjdescription		setf jjdescription
 
 " Jovial
 au BufNewFile,BufRead *.jov,*.j73,*.jovial	setf jovial
diff --git a/runtime/ftplugin/jj.vim b/runtime/ftplugin/jjdescription.vim
similarity index 100%
rename from runtime/ftplugin/jj.vim
rename to runtime/ftplugin/jjdescription.vim
diff --git a/runtime/syntax/jj.vim b/runtime/syntax/jjdescription.vim
similarity index 94%
rename from runtime/syntax/jj.vim
rename to runtime/syntax/jjdescription.vim
index 0b2d29e..04848bc 100644
--- a/runtime/syntax/jj.vim
+++ b/runtime/syntax/jjdescription.vim
@@ -21,4 +21,4 @@
 hi def link jjRemoved Removed
 hi def link jjChanged Changed
 
-let b:current_syntax = 'jj'
+let b:current_syntax = 'jjdescription'