Add Railgun theme (#4393)

Railgun dark theme suite for Zed based on the [VSC
Railgun](https://github.com/be5invis/vsc-theme-railgun).

Co-authored-by: MrSubidubi <[email protected]>

Author: Al-Pharaday

.gitmodules

@@ -2750,6 +2750,10 @@
 	path = extensions/racket
 	url = https://github.com/zed-extensions/racket.git
 
+[submodule "extensions/railgun"]
+	path = extensions/railgun
+	url = https://github.com/Al-Pharaday/zed-theme-railgun
+
 [submodule "extensions/railscast"]
 	path = extensions/railscast
 	url = https://github.com/pbsds/railscast-zed.git

extensions.toml

@@ -2789,6 +2789,10 @@ version = "0.2.5"
 submodule = "extensions/racket"
 version = "0.1.1"
 
+[railgun]
+submodule = "extensions/railgun"
+version = "1.0.0"
+
 [railscast]
 submodule = "extensions/railscast"
 version = "0.1.0"