update README with the minimum info

Author: jdlph

README.md

@@ -0,0 +1,55 @@
+# TAPLite
+
+TAPLite is a lightweight traffic assignment and simulation engine for networks encoded in GMNS.
+
+## Quick Start
+
+### Installation
+```
+pip install taplite
+```
+
+### Traffic Assignment
+
+#### One-Time Call
+```
+import taplite as tap
+
+tap.assignment()
+```
+
+#### Recursive Call
+```
+import taplite as tap
+from multiprocessing import freeze_support
+
+if __name__ == '__main__':
+    freeze_support()
+
+    while True:
+        tap.assignment()
+```
+
+### Traffic Simulation
+
+Note that assignment() must be invoked in the same code block prior to simulation().
+```
+import taplite as tap
+
+tap.assignment()
+tap.simulation()
+```
+## Build TAPLite from Scratch
+
+**1. Build the C++ Shared Library**
+
+```
+# from the root directory of TAPLite
+cmake -S . -B build -DBUILD_EXE=OFF
+cmake --build build
+```
+**2. Build and Install the Python Package**
+```
+# from the root directory of TAPLite
+python -m pip install .
+```