Replace tab characters with two spaces

Several documents in this repo mandate using soft-tabs with a two-space indent,
so it seems only sensible to do it in this file too.

use-of-READMEs.md

@@ -77,18 +77,18 @@ Keep this section limited to core endpoints - if the app is complex link out to
 ## Things we shouldn't put in the README
 
 - Full documentation of the API - if the app is complex or has a complex API, use the `docs` directory liberally, and link out to it from the `README`
-	- If the API is small try to keep it in the main README and don't link to docs
-	- Some bad examples - too much documentation in the README:
-		- [smart-answers](https://github.com/alphagov/smart-answers/blob/06dfeb854ec9728374186a2e37c1eb62a5aaa49a/README.md)
-		- [govuk_frontend_toolkit](https://github.com/alphagov/govuk_frontend_toolkit/blob/edd834de8d2f4e854475f5d226aa0cd260795cef/README.md)
-	- Good examples:
-		- [content-store](https://github.com/alphagov/content-store/blob/b244620f505f248fc93d8556eedad14b5cba1187/README.md) - links out to more docs as required
-		- [modern smart-answers](https://github.com/alphagov/smart-answers/blob/c0b4580d18ccc5004abfa7015017d26e1a73f2aa/README.md) - links out to more docs as required
-	- For Ruby libraries always use [yardoc](http://yardoc.org/) - then Gems will automatically have docs built
+  - If the API is small try to keep it in the main README and don't link to docs
+  - Some bad examples - too much documentation in the README:
+    - [smart-answers](https://github.com/alphagov/smart-answers/blob/06dfeb854ec9728374186a2e37c1eb62a5aaa49a/README.md)
+    - [govuk_frontend_toolkit](https://github.com/alphagov/govuk_frontend_toolkit/blob/edd834de8d2f4e854475f5d226aa0cd260795cef/README.md)
+  - Good examples:
+    - [content-store](https://github.com/alphagov/content-store/blob/b244620f505f248fc93d8556eedad14b5cba1187/README.md) - links out to more docs as required
+    - [modern smart-answers](https://github.com/alphagov/smart-answers/blob/c0b4580d18ccc5004abfa7015017d26e1a73f2aa/README.md) - links out to more docs as required
+  - For Ruby libraries always use [yardoc](http://yardoc.org/) - then Gems will automatically have docs built
 - Contributors - we can use GitHub's native graphing tools for this
 - Contribution guidelines - use GitHub's [CONTRIBUTING.md](https://help.github.com/articles/setting-guidelines-for-repository-contributors/) guidelines for this
-	- When writing this document, always link to the [GOV.UK pull request styleguide](https://github.com/alphagov/styleguides/blob/master/pull-requests.md)
-	- Document any weirdness here (eg when to use Cucumber over something else)
+  - When writing this document, always link to the [GOV.UK pull request styleguide](https://github.com/alphagov/styleguides/blob/master/pull-requests.md)
+  - Document any weirdness here (eg when to use Cucumber over something else)
 - Full licence - again, follow [GitHub convention](https://help.github.com/articles/open-source-licensing/#where-does-the-license-live-on-my-repository)
 
 ## One-line summaries on GitHub repositories