Document empty sections

Author: brson

README.md

@@ -44,13 +44,7 @@ mod errors;
 Add a file for that module called `errors.rs` and put this inside:
 
 ```rust
-error_chain! {
-    links { }
-
-    foreign_links { }
-
-    errors { }
-}
+error_chain! { }
 ```
 
 That's the setup. Now when writing modules for your crate,

src/lib.rs

@@ -84,13 +84,7 @@
 //! Add a file for that module called `errors.rs` and put this inside:
 //!
 //! ```ignore
-//! error_chain! {
-//!     links { }
-//!
-//!     foreign_links { }
-//!
-//!     errors { }
-//! }
+//! error_chain! { }
 //! ```
 //!
 //! That's the setup. Now when writing modules for your crate,
@@ -166,6 +160,9 @@
 //! }
 //! ```
 //!
+//! Each section, `types`, `links`, `foreign_links`, and `errors` may
+//! be omitted if it is empty.
+//!
 //! This populates the module with a number of definitions,
 //! the most important of which are the `Error` type
 //! and the `ErrorKind` type. They look something like the

tests/tests.rs

@@ -104,6 +104,11 @@ fn smoke_test_7() {
     }
 }
 
+#[test]
+fn empty() {
+    error_chain! { }
+}
+
 #[cfg(test)]
 mod foreign_link_test {