patch 8.1.0528: various typos in comments

Problem:    Various typos in comments.
Solution:   Fix the typos.
diff --git a/src/INSTALL b/src/INSTALL
index 99f1047..3da9141 100644
--- a/src/INSTALL
+++ b/src/INSTALL
@@ -11,10 +11,10 @@
 
 See INSTALLami.txt              for Amiga
 See INSTALLmac.txt              for Macintosh
-See INSTALLpc.txt               for PC (Windows 95/98/NT/XP/Vista/7/8/10)
+See INSTALLpc.txt               for PC (Windows XP/Vista/7/8/10)
 See INSTALLvms.txt              for VMS
 See INSTALLx.txt		for cross-compiling on Unix
-See ../README_390.txt           for OS/390 Unix
+See ../READMEdir/README_390.txt for z/OS and OS/390 Unix
 See ../runtime/doc/os_beos.txt  for BeBox