Update version numbers in the book (#697)

I also added a note to `Cargo.toml` to remind about incrementing these
nubers across the book. This is important as users won’t always take a
note of what is the most recent release is when reading the book.

Cargo.toml

@@ -4,6 +4,9 @@ authors = [
   "Brook Heisler <brookheisler@gmail.com>",
 ]
 name = "criterion"
+# When bumping:
+#
+# * Update version numbers in the book;
 version = "0.5.1"
 edition = "2018"
 

book/src/getting_started.md

@@ -21,7 +21,7 @@ To enable Criterion.rs benchmarks, add the following to your `Cargo.toml` file:
 
 ```toml
 [dev-dependencies]
-criterion = "0.4"
+criterion = "0.5.1"
 
 [[bench]]
 name = "my_benchmark"

book/src/user_guide/custom_test_framework.md

@@ -3,9 +3,9 @@
 Nightly versions of the rust compiler support custom test frameworks. Criterion.rs provides an
 experimental implementation of a custom test framework, meaning that you can use `#[criterion]`
 attributes to mark your benchmarks instead of the normal `criterion_group!/criterion_main!` macros.
-Right now this requires some unstable features, but at some point in the future 
+Right now this requires some unstable features, but at some point in the future
 `criterion_group!/criterion_main!` will be deprecated and `#[criterion]` will become the standard
-way to define a Criterion.rs benchmark. If you'd like to try this feature out early, see the 
+way to define a Criterion.rs benchmark. If you'd like to try this feature out early, see the
 documentation below.
 
 ## Using `#[criterion]`

book/src/user_guide/migrating_from_libtest.md

@@ -42,7 +42,7 @@ We also need to add Criterion.rs to the `dev-dependencies` section of `Cargo.tom
 
 ```toml
 [dev-dependencies]
-criterion = "0.4"
+criterion = "0.5.1"
 ```
 
 The next step is to update the imports: