Redo headings in test suite readme

spec/README.md

@@ -1,8 +1,10 @@
 # Running Mongoid Tests
 
-## Overview
-### Quick Start
-Spin up a MongoDB deployment against which to run the Mongoid specs. Mongoid specs support a variety of MongoDB topologies, but the simplest is a single MongoDB instance:
+## Quick Start
+
+Spin up a MongoDB deployment against which to run the Mongoid specs.
+Mongoid specs support a variety of MongoDB topologies, but the simplest is
+a single MongoDB instance:
 
     # Launch mongod in one terminal
     mkdir /tmp/mdb
@@ -14,5 +16,11 @@ Run the test suite in a separate terminal:
 
 
 ## Caveats
+
 ### "Too many open files" error
-On MacOS, you may encounter a "Too many open files" error on the MongoDB server when running the tests. If this happens, stop the server, run the command `ulimit -n 10000` in the same terminal session as the server, and restart the server. This will increase the number of files that can be opened. Then, re-run the tests.
+
+On MacOS, you may encounter a "Too many open files" error on the MongoDB server
+when running the tests. If this happens, stop the server, run the command
+`ulimit -n 10000` in the same terminal session as the server, and restart
+the server. This will increase the number of files that can be opened.
+Then, re-run the tests.