more documentation and formatting

booksrc/SUMMARY.md

@@ -5,7 +5,7 @@
 - [Simple String Errors](tutorial1.md)
 - [Simple Chained String Errors](tutorial2.md)
 - [Mapping Errors](tutorial3.md)
-- [Saving coding chars](tutorial4.md)
+- [More Information](tutorial4.md)
 - [The source() of Errors](tutorial5.md)
 - [Downcast the Errors](tutorial6.md)
 - [The root cause of all Errors](tutorial7.md)
@@ -17,4 +17,4 @@
 - [Writing a library](tutorial13.md)
 - [Going back to std](tutorial14.md)
 
-[The End](end.md)
+[The End](end.md)

booksrc/tutorial10.md

@@ -5,9 +5,6 @@ To cope with different kind of errors, we introduce the kind of an error `Func1E
 Because we derive `Debug` and implement `Display` our `Func1ErrorKind` enum, this enum can be used as
 a `std::error::Error`.
 
-Not using `String` errors anymore, the `context()` function seen in the beginning of
-the tutorial can be used again.
-
 Only returning `Func1ErrorKind` in `func1()` now let us get rid of `Result<(), Box<Error + Send + Sync>>` and we can
 use `ChainResult<(), Func1ErrorKind>`.
 

booksrc/tutorial11.md

@@ -1,6 +1,6 @@
 # Debug for the ErrorKind
 
-One small improvement at the end of the tutorial is to fix the debug output of
+One small improvement is to fix the debug output of
 `Func1ErrorKind`. As you probably noticed, the output doesn't say much of the enum.
 
 ~~~