doc: remove references to 'term' and other tty related options.

Re: https://github.com/neovim/neovim/issues/4218

runtime/doc/options.txt

@@ -50,8 +50,8 @@ achieve special effects.  These options come in three forms:
 :se[t] {option}&vim	Reset option to its Vim default value.
 
 :se[t] all&		Set all options, except terminal options, to their
-			default value.  The values of 'term', 'lines' and
-			'columns' are not changed.
+			default value.  The values of 'lines' and 'columns'
+			are not changed.
 
 						*:set-args* *E487* *E521*
 :se[t] {option}={value}		or
@@ -772,14 +772,13 @@ A jump table for the options with a short description can be found at |Q_op|.
 	putting a ":gui" command in the gvimrc file, before where the value
 	of 'background' is used (e.g., before ":syntax on").
 
-	For Windows the default is "dark".
-	For other systems "dark" is used when 'term' is "linux",
-	"screen.linux", "cygwin" or "putty", or $COLORFGBG suggests a dark
-	background.  Otherwise the default is "light".
+	For Windows the default is "dark". "dark" should be used if $COLORFGBG
+	suggests a dark	background (not yet implemented). Otherwise the default
+	is "light".
 
 	Normally this option would be set in the vimrc file.  Possibly
 	depending on the terminal name.  Example: >
-		:if &term == "xterm"
+		:if $TERM == "xterm"
 		:  set background=dark
 		:endif
 <	When this option is set, the default settings for the highlight groups
@@ -6371,17 +6370,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	mapping which should not change the tagstack.
 
 						*'term'* *E529* *E530* *E531*
-'term'			string	(default is $TERM, if that fails:
-				      in the GUI: "builtin_gui"
-					  on Mac: "mac-ansi"
-					 on Unix: "ansi"
-				       on Windows: "win32")
-			global
-	Name of the terminal.  Used for choosing the terminal control
-	characters.  Environment variables are expanded |:set_env|.
-	For example: >
-		:set term=$TERM
-<	See |termcap|.
+'term'			Removed. |vim-differences| {Nvim}
 
 						*'termbidi'* *'tbidi'*
 						*'notermbidi'* *'notbidi'*
@@ -6561,9 +6550,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 'ttyscroll' 'tsl'	Removed. |vim-differences| {Nvim}
 
 						*'ttytype'* *'tty'*
-'ttytype' 'tty'		string	(default from $TERM)
-			global
-	Alias for 'term', see above.
+'ttytype' 'tty'		Alias for 'term'. Removed. |vim-differences| {Nvim}
 
 						*'undodir'* *'udir'* *E926*
 'undodir' 'udir'	string	(default "$XDG_DATA_HOME/nvim/undo")

runtime/doc/starting.txt

@@ -217,7 +217,7 @@ argument.
 			:set      to display option values.
 		When 'verbose' is non-zero messages are printed (for
 		debugging, to stderr).
-		'term' and $TERM are not used.
+		$TERM is not used.
 		If Vim appears to be stuck try typing "qa!<Enter>".  You don't
 		get a prompt thus you can't see Vim is waiting for you to type
 		something.
@@ -354,13 +354,10 @@ argument.
 At startup, Vim checks environment variables and files and sets values
 accordingly.  Vim proceeds in this order:
 
-1. Set the 'shell' and 'term' option		*SHELL* *COMSPEC* *TERM*
+1. Set the 'shell' option		*SHELL* *COMSPEC* *TERM*
 	The environment variable SHELL, if it exists, is used to set the
 	'shell' option.  On Windows, the COMSPEC variable is used
 	if SHELL is not set.
-	The environment variable TERM, if it exists, is used to set the 'term'
-	option.  However, 'term' will change later when starting the GUI (step
-	8 below).
 
 2. Process the arguments
 	The options and file names from the command that start Vim are
@@ -705,8 +702,8 @@ vimrc file.
 These commands will write ":map" and ":set" commands to a file, in such a way
 that when these commands are executed, the current key mappings and options
 will be set to the same values.  The options 'columns', 'endofline',
-'fileformat', 'lines', 'modified', 'scroll', and 'term' are not included,
-because these are terminal or file dependent.
+'fileformat', 'lines', 'modified', and 'scroll' are not included, because 
+these are terminal or file dependent.
 Note that the options 'binary', 'paste' and 'readonly' are included, this
 might not always be what you want.
 

runtime/doc/vim_diff.txt

@@ -207,6 +207,7 @@ Other options:
   'shelltype'
   'shortname'
   'swapsync'
+  'term'
   'termencoding' (Vim 7.4.852 also removed this for Windows)
   'textauto'
   'textmode'
@@ -214,6 +215,8 @@ Other options:
   'toolbariconsize'
   'ttybuiltin'
   'ttymouse'
+  'ttyscroll'
+  'ttytype'
   'weirdinvert'
 
 Other commands: