README: add <> around links

Some markdown renderers want <> around links to linkify them.
Other renderers strip them out as redundant.

Change-Id: Ib7f9962ce1dd47b4494a824c69358c75d98eb838
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/255312
Reviewed-by: David Pursehouse <dpursehouse@collab.net>
Tested-by: Mike Frysinger <vapier@google.com>

README.md

@@ -6,11 +6,11 @@ development workflow.  Repo is not meant to replace Git, only to make it
 easier to work with Git.  The repo command is an executable Python script
 that you can put anywhere in your path.
 
-* Homepage: https://gerrit.googlesource.com/git-repo/
-* Bug reports: https://bugs.chromium.org/p/gerrit/issues/list?q=component:repo
-* Source: https://gerrit.googlesource.com/git-repo/
-* Overview: https://source.android.com/source/developing.html
-* Docs: https://source.android.com/source/using-repo.html
+* Homepage: <https://gerrit.googlesource.com/git-repo/>
+* Bug reports: <https://bugs.chromium.org/p/gerrit/issues/list?q=component:repo>
+* Source: <https://gerrit.googlesource.com/git-repo/>
+* Overview: <https://source.android.com/source/developing.html>
+* Docs: <https://source.android.com/source/using-repo.html>
 * [repo Manifest Format](./docs/manifest-format.md)
 * [repo Hooks](./docs/repo-hooks.md)
 * [Submitting patches](./SUBMITTING_PATCHES.md)