More nested list formatting

It looks like GitHub requires the nested list to be indented to the same
level as the text after the number.

Author: randycoulman

README.md

@@ -127,9 +127,9 @@ Here's a rough outline:
 9. [Debugging with testdouble.js](docs/9-debugging.md#debugging-with-testdoublejs)
    1. [td.explain() API](docs/9-debugging.md#tdexplainsometestdouble)
 10. [Plugins](docs/A-plugins.md#plugins)
-   1. [testdouble-chai](https://github.com/basecase/testdouble-chai)
-   2. [testdouble-jasmine](https://github.com/BrianGenisio/testdouble-jasmine)
+    1. [testdouble-chai](https://github.com/basecase/testdouble-chai)
+    2. [testdouble-jasmine](https://github.com/BrianGenisio/testdouble-jasmine)
 11. [Frequently Asked Questions](docs/B-frequently-asked-questions.md#frequently-asked-questions)
-   1. [Why doesn't `td.replace()` work with external CommonJS modules?](docs/B-frequently-asked-questions.md#why-doesnt-tdreplace-work-with-external-commonjs-modules)
+    1. [Why doesn't `td.replace()` work with external CommonJS modules?](docs/B-frequently-asked-questions.md#why-doesnt-tdreplace-work-with-external-commonjs-modules)
 12. [Configuration](docs/C-configuration.md#configuration)
-   1. [td.config](docs/C-configuration.md#tdconfig)
+    1. [td.config](docs/C-configuration.md#tdconfig)