patch 8.2.1262: src/ex_cmds.c file is too big

Problem:    src/ex_cmds.c file is too big.
Solution:   Move help related code to src/help.c. (Yegappan Lakshmanan,
            closes #6506)
diff --git a/src/Make_vms.mms b/src/Make_vms.mms
index 78f9dab..0d80c06 100644
--- a/src/Make_vms.mms
+++ b/src/Make_vms.mms
@@ -337,6 +337,7 @@
 	gui_xim.c \
 	hardcopy.c \
 	hashtab.c \
+	help.c \
 	highlight.c \
 	if_cscope.c \
 	if_xcmdsrv.c \
@@ -450,6 +451,7 @@
 	gui_xim.obj \
 	hardcopy.obj \
 	hashtab.obj \
+	help.obj \
 	highlight.obj \
 	if_cscope.obj \
 	if_mzsch.obj \
@@ -834,6 +836,10 @@
  ascii.h keymap.h term.h macros.h structs.h regexp.h \
  gui.h beval.h [.proto]gui_beval.pro option.h ex_cmds.h proto.h \
  globals.h
+help.obj : help.c vim.h [.auto]config.h feature.h os_unix.h \
+ ascii.h keymap.h term.h macros.h structs.h regexp.h \
+ gui.h beval.h [.proto]gui_beval.pro option.h ex_cmds.h proto.h \
+ globals.h
 highlight.obj : highlight.c vim.h [.auto]config.h feature.h os_unix.h \
  ascii.h keymap.h term.h macros.h structs.h regexp.h \
  gui.h beval.h [.proto]gui_beval.pro option.h ex_cmds.h proto.h \