Adds basic IB surgery instructions to surgical case (#4121)

# About the pull request

Adds basic IB surgery instructions to surgical case

# Explain why it's good for the game

In character ability to learn the game good

# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

Put screenshots and videos here with an empty line between the
screenshots and the `<details>` tags.

</details>


# Changelog

:cl:
add: Added basic IB surgery instructions to surgical case
/:cl:

code/game/objects/items/storage/firstaid.dm

@@ -265,7 +265,14 @@
 
 /obj/item/storage/surgical_case
 	name = "surgical case"
-	desc = "It's a medical case for storing basic surgical tools."
+	desc = "It's a medical case for storing basic surgical tools. It comes with a brief description for treating common internal bleeds.\
+		\nBefore surgery: Verify correct location and patient is adequately numb to pain.\
+		\nStep one: Open an incision at the site with the scalpel.\
+		\nStep two: Clamp bleeders with the hemostat.\
+		\nStep three: Draw back the skin with the retracter.\
+		\nStep four: Patch the damaged vein with a surgical line.\
+		\nStep five: Close the incision with a surgical line."
+
 	icon_state = "surgical_case"
 	throw_speed = SPEED_FAST
 	throw_range = 8