doc: update environment vars in manpage and --help

- Added NODE_REPL_HISTORY to the environment variables in the --help
  and made all descriptions start with lower case for consistency.

- Added NODE_REPL_HISTORY and NODE_ICU_DATA to the man page.

PR-URL: #2690
Reviewed-By: fishrock123 - Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: evanlucas - Evan Lucas <evanlucas@me.com>

doc/node.1

@@ -72,9 +72,15 @@ and servers.
 
 .IP NODE_PATH
 \':\'\-separated list of directories prefixed to the module search path.
-
 .IP NODE_DISABLE_COLORS
 If set to 1 then colors will not be used in the REPL.
+.IP NODE_ICU_DATA
+Data path for ICU (Intl object) data. Will extend linked-in data when compiled
+with small-icu support.
+.IP NODE_REPL_HISTORY
+Path to the file used to store the persistent REPL history. The default path
+is ~/.node_repl_history, which is overridden by this variable. Setting the
+value to an empty string ("") disables persistent REPL history.
 
 .SH V8 OPTIONS
 

src/node.cc

@@ -3066,7 +3066,7 @@ static void PrintHelp() {
          "  --icu-data-dir=dir    set ICU data load path to dir\n"
          "                        (overrides NODE_ICU_DATA)\n"
 #if !defined(NODE_HAVE_SMALL_ICU)
-         "                        Note: linked-in ICU data is\n"
+         "                        note: linked-in ICU data is\n"
          "                        present.\n"
 #endif
 #endif
@@ -3078,13 +3078,14 @@ static void PrintHelp() {
          "NODE_PATH               ':'-separated list of directories\n"
 #endif
          "                        prefixed to the module search path.\n"
-         "NODE_DISABLE_COLORS     Set to 1 to disable colors in the REPL\n"
+         "NODE_DISABLE_COLORS     set to 1 to disable colors in the REPL\n"
 #if defined(NODE_HAVE_I18N_SUPPORT)
-         "NODE_ICU_DATA           Data path for ICU (Intl object) data\n"
+         "NODE_ICU_DATA           data path for ICU (Intl object) data\n"
 #if !defined(NODE_HAVE_SMALL_ICU)
          "                        (will extend linked-in data)\n"
 #endif
 #endif
+         "NODE_REPL_HISTORY       path to the persistent REPL history file\n"
          "\n"
          "Documentation can be found at https://nodejs.org/\n");
 }