Add README.md

README.md

+# BPFtrace
+
+BPFtrace is currently a work in progress and can not currently run scripts. The examples below are to give an idea of what the final result should be.
+
+## Examples
+
+To produce a histogram of amount of time spent in the read() system call:
+```
+kprobe:sys_read
+{
+  @start[tid] = nsecs;
+}
+
+kretprobe:sys_read / @start[tid] /
+{
+  @times = quantize(nsecs - @start[tid]);
+  @start[tid] = 0;
+}
+```
+
+
+# Building
+
+## Requirements
+- A C++ compiler
+- CMake
+- Flex
+- Bison
+- LLVM
+
+## Compilation
+Compile using CMake, optionally substituting "Release" for "Debug" as CMAKE\_BUILD\_TYPE:
+```
+git clone https://github.com/ajor/bpftrace.git
+cd bpftrace
+mkdir build
+cd build
+cmake -DCMAKE_BUILD_TYPE=Debug ../src
+make
+```