Fix `toolchain` typo in bazel-and-java.md
The "Java and Bazel" page twice referenced a method
`register_toolchain` which contains a typo. The method's correct name is
`register_toolchains`, with a plural "s".
Closes
@@ -231,7 +231,7 @@ LCOV format.
The `TestRunner` tool executes JUnit 4 tests in a controlled environment.
You can reconfigure the compilation by adding `default_java_toolchain` macro to
-a `BUILD` file and registering it either by adding `register_toolchain` rule to
+a `BUILD` file and registering it either by adding `register_toolchains` rule to
the `WORKSPACE` file or by using
[`--extra_toolchains`](/docs/user-manual#extra-toolchains) flag.
@@ -258,7 +258,7 @@ default_java_toolchain(
```
which can be used using `--extra_toolchains=//:repository_default_toolchain_definition`
-or by adding `register_toolchain("//:repository_default_toolchain_definition")`
+or by adding `register_toolchains("//:repository_default_toolchain_definition")`
to the workpace.
Predefined configurations:
