adding jit example

Signed-off-by: Alex McCaskey <mccaskeyaj@ornl.gov>

examples/qjit/bell_jit.cpp

+// To use the QCOR JIT utilities 
+// just include the qcor_jit.hpp header
+#include "qcor_jit.hpp"
+
+int main() {
+
+  // QJIT is the entry point to QCOR quantum kernel 
+  // just in time compilation
+  QJIT qjit;
+
+  // Define a quantum kernel string dynamically
+  const auto kernel_src = R"#(__qpu__ void bell(qreg q) {
+        using qcor::openqasm;
+        h q[0];
+        cx q[0], q[1];
+        creg c[2];
+        measure q -> c;
+    })#";
+
+  // Use the QJIT instance to compile this at runtime
+  qjit.jit_compile(kernel_src);
+
+  // Now, one can get the compiled kernel as a 
+  // functor to execute, must provide the kernel 
+  // argument types as template parameters
+  auto bell_functor = qjit.get_kernel<qreg>("bell");
+
+  // Allocate some qubits and run the kernel functor
+  auto q = qalloc(2);
+  bell_functor(q);
+  q.print();
+
+  // Or, one can call the QJIT invoke method 
+  // with the name of the kernel function and 
+  // the necessary function arguments.
+  auto r = qalloc(2);
+  qjit.invoke("bell", r);
+  r.print();
+
+  // Note, if QCOR QJIT has not seen this kernel 
+  // source code before, it will run through the 
+  // entire JIT compile process. If you have run 
+  // this JIT compile before, QCOR QJIT will read a 
+  // cached representation of the kernel and load that, 
+  // increasing JIT compile performance. 
+}
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examples/qjit/qcor_jit_test.cpp

-
-#include "qcor.hpp"
-#include "qcor_jit.hpp"
-int main() {
-
-  QJIT qjit;
-  qjit.jit_compile(R"#(__qpu__ void bell(qreg q) {
-        printf("hello world\n");
-        using qcor::openqasm;
-        h q[0];
-        cx q[0], q[1];
-        creg c[2];
-        measure q -> c;
-    })#");
-
-  auto q = qalloc(2);
-  qjit.invoke("bell", q);
-
-  q.print();
-}
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