Gentle formatting fixes we can run more often. (#443)

Fixes a bunch of inadvertently preformatted text due to >4 spaces after a bullet.

admin/reformat-aggressive.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+# Put main main Markdown files into canonical syntax (in place!) with markdownfmt.
+# XXX This is aggressive so we haven't been running. See also 
+# https://github.com/shurcooL/markdownfmt/issues?utf8=%E2%9C%93&q=is%3Aopen%20author%3Ajlevy%20
+
+set -e -u -o pipefail
+
+hash markdownfmt >/dev/null 2>&1 || {
+  echo >&2 "markdownfmt missing: Install https://github.com/shurcooL/markdownfmt and re-run"
+  exit 1
+}
+
+cd $(dirname $0)/..
+
+markdownfmt -w README.md CONTRIBUTING.md