patch 8.1.2086: missing a few changes for the renamed files

Problem:    Missing a few changes for the renamed files.
Solution:   Rename in a few more places. (Ken Takata)
diff --git a/src/GvimExt/README.txt b/src/GvimExt/README.txt
index 4a75cfa..a29200e 100644
--- a/src/GvimExt/README.txt
+++ b/src/GvimExt/README.txt
@@ -11,7 +11,7 @@
 
 In special situations you might want to make changes by hand.  Check these
 items:
-- The gvimext.dll, gvim.exe and uninstal.exe either need to be in the search
+- The gvimext.dll, gvim.exe and uninstall.exe either need to be in the search
   path, or you have to set the full path in the registry entries.  You could
   move the gvimext.dll to the "windows\system" or "windows\system32"
   directory, where the other DLL files are.