[nit] Fix a readme typo. (#115)

README.md

@@ -5,7 +5,7 @@
 Left-right is a concurrency primitive for high concurrency reads over a
 single-writer data structure. The primitive keeps two copies of the
 backing data structure, one that is accessed by readers, and one that is
-access by the (single) writer. This enables all reads to proceed in
+accessed by the (single) writer. This enables all reads to proceed in
 parallel with minimal coordination, and shifts the coordination overhead
 to the writer. In the absence of writes, reads scale linearly with the
 number of cores.