fix README markdown better

README.md

@@ -33,19 +33,19 @@ This repository contains the following case studies:
 * [logrel](theories/logrel): Logical relations from the
   [IPM paper](http://doi.acm.org/10.1145/3093333.3009855):
   - STLC
-    - Unary logical relations proving type safety
+      - Unary logical relations proving type safety
   - F_mu (System F with recursive types)
-    - Unary logical relations proving type safety
+      - Unary logical relations proving type safety
   - F_mu_ref (System F with recursive types and references)
-    - Unary logical relations proving type safety
-    - Binary logical relations for proving contextual refinements
+      - Unary logical relations proving type safety
+      - Binary logical relations for proving contextual refinements
   - F_mu_ref_conc (System F with recursive types, references and concurrency)
-    - Unary logical relations proving type safety
-    - Binary logical relations for proving contextual refinements
-      - Proof of refinement for a pair of fine-grained/coarse-grained concurrent
-        counter implementations
-      - Proof of refinement for a pair of fine-grained/coarse-grained concurrent
-        stack implementations
+      - Unary logical relations proving type safety
+      - Binary logical relations for proving contextual refinements
+          - Proof of refinement for a pair of fine-grained/coarse-grained
+            concurrent counter implementations
+          - Proof of refinement for a pair of fine-grained/coarse-grained
+            concurrent stack implementations
 * [spanning-tree](theories/spanning_tree): Proof of a concurrent spanning tree
   algorithm.
 * [lecture-notes](theories/lecture_notes): Coq examples for the