Created Perl EVENT_ENTER (markdown)

Perl-EVENT_ENTER.md

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+EVENT_ENTER is triggered when a player moves into proximity of the NPC.  Proximity is defined by quest::set_proximity(min_x, max_x, min_y, max_y, min_z, max_z).  
+
+See [quest::set_proximity](https://github.com/EQEmu/Server/wiki/Perl-Quest-set_proximity) for more information on setting a proximity.
+
+### Exports
+
+### Triggered
+
+* When a player moves into proximity of the NPC
+
+### Examples
+
+* This example establishes the NPC's proximity and checks to see if the player has an item before the NPC speaks.
+
+```perl
+sub EVENT_SPAWN {
+     #:: Set the proximity bounds around the NPC on spawn, 15 unit radius
+     my $x;
+     my $y;
+     $x = $npc->GetX();
+     $y = $npc->GetY();
+     quest::set_proximity($x-15,$x+15,$y-15,$y+15);
+}
+
+sub EVENT_ENTER {
+     #::: Check and see if the player who enters is carrying Item ID 17005 - Backpack
+     if (plugin::check_hasitem($client, 17005)) {
+          quest::say("Hey, nice backpack!");
+     }
+}
+```