add intro to README (taken from google code site)

README.md

@@ -1,4 +1,11 @@
 
+# httperf
+
+httperf is a tool for measuring web server performance. It provides a flexible facility for generating various HTTP workloads and for measuring server performance.
+
+The focus of httperf is not on implementing one particular benchmark but on providing a robust, high-performance tool that facilitates the construction of both micro- and macro-level benchmarks. The three distinguishing characteristics of httperf are its robustness, which includes the ability to generate and sustain server overload, support for the HTTP/1.1 and SSL protocols, and its extensibility to new workload generators and performance measurements.
+
+
 ## Building httperf
 
 This release of httperf is using the standard GNU configuration