diff --git a/book/src/SUMMARY.md b/book/src/SUMMARY.md
index 0f600b4..348dea7 100644
--- a/book/src/SUMMARY.md
+++ b/book/src/SUMMARY.md
@@ -2,30 +2,29 @@
 
 - [Introduction](./introduction.md)
 - [Runtimes](./runtimes.md)
-    - [Lua](./lua/lua.md)
-        - [Installation](./lua/installation.md)
-        - [Hello World](./lua/hello_world.md)
-        - [Spawning scripts](./lua/spawning_scripts.md)
-        - [Calling Rust from Lua](./lua/calling_rust_from_script.md)
-        - [Calling Lua from Rust](./lua/calling_script_from_rust.md)
-        - [Interacting with bevy in callbacks](./lua/interacting_with_bevy.md)
-        - [Builtin types](./lua/builtin_types.md)
-        - [Builtin variables](./lua/builtin_variables.md)
-    - [Ruby](./ruby/ruby.md)
-        - [Installation](./ruby/installation.md)
-        - [Hello World](./ruby/hello_world.md)
-        - [Spawning scripts](./ruby/spawning_scripts.md)
-        - [Calling Rust from Ruby](./ruby/calling_rust_from_script.md)
-        - [Calling Ruby from Rust](./ruby/calling_script_from_rust.md)
-        - [Interacting with bevy in callbacks](./ruby/interacting_with_bevy.md)
-        - [Builtin types](./ruby/builtin_types.md)
-        - [Builtin variables](./ruby/builtin_variables.md)
-    - [Rhai](./rhai/rhai.md)
-        - [Installation](./rhai/installation.md)
-        - [Hello World(TBD)]()
+  - [Lua](./lua/lua.md)
+    - [Installation](./lua/installation.md)
+    - [Hello World](./lua/hello_world.md)
+    - [Spawning scripts](./lua/spawning_scripts.md)
+    - [Calling Rust from Lua](./lua/calling_rust_from_script.md)
+    - [Calling Lua from Rust](./lua/calling_script_from_rust.md)
+    - [Interacting with bevy in callbacks](./lua/interacting_with_bevy.md)
+    - [Builtin types](./lua/builtin_types.md)
+    - [Builtin variables](./lua/builtin_variables.md)
+  - [Ruby](./ruby/ruby.md)
+    - [Installation](./ruby/installation.md)
+    - [Hello World](./ruby/hello_world.md)
+    - [Spawning scripts](./ruby/spawning_scripts.md)
+    - [Calling Rust from Ruby](./ruby/calling_rust_from_script.md)
+    - [Calling Ruby from Rust](./ruby/calling_script_from_rust.md)
+    - [Interacting with bevy in callbacks](./ruby/interacting_with_bevy.md)
+    - [Builtin types](./ruby/builtin_types.md)
+  - [Rhai](./rhai/rhai.md)
+    - [Installation](./rhai/installation.md)
+    - [Hello World(TBD)]()
 - [Multiple plugins](./multiple_plugins.md)
 - [Multiple runtimes(TBD)]()
 - [Implementing custom runtimes(TBD)]()
 - [Workflow](./workflow/workflow.md)
-    - [Live-reload](./workflow/live_reload.md)
+  - [Live-reload](./workflow/live_reload.md)
 - [Bevy support matrix](./bevy_support_matrix.md)
diff --git a/book/src/ruby/builtin_types.md b/book/src/ruby/builtin_types.md
index a661888..dd48962 100644
--- a/book/src/ruby/builtin_types.md
+++ b/book/src/ruby/builtin_types.md
@@ -55,6 +55,8 @@ fn set_translation(
 
 ## Bevy::Entity
 
+`Bevy::Entity.current` is currently not available within promise callbacks.
+
 ### Constructor
 
 None - instances can only be acquired by using `Bevy::Entity.current`
diff --git a/book/src/ruby/builtin_variables.md b/book/src/ruby/builtin_variables.md
index 2896ecf..a857bfe 100644
--- a/book/src/ruby/builtin_variables.md
+++ b/book/src/ruby/builtin_variables.md
@@ -1,13 +1 @@
 # Builtin variables
-
-## entity
-
-Current entity that the script is atteched to can be retrieved by calling `Bevy::Entity.current`.
-It exposes `index` method that returns bevy entity index.
-It is useful for accessing entity's components from scripts.
-It can be used in the following way:
-```ruby
-puts("Current entity index: #{Bevy::Entity.current.index}")
-```
-
-`Bevy::Entity.current` variable is currently not available within promise callbacks.