Update static-items.md

"All access to a static is safe" -> "All access to an immutable static is safe"

Author: Coder-256

src/items/static-items.md

@@ -12,7 +12,7 @@ other lifetimes in a Rust program. Non-`mut` static items that contain a type
 that is not [interior mutable] may be placed in read-only memory. Static items
 do not call [`drop`] at the end of the program.
 
-All access to a static is safe, but there are a number of restrictions on
+All access to an immutable static is safe, but there are a number of restrictions on
 statics:
 
 * The type must have the `Sync` trait bound to allow thread-safe access.