add citation for MICRO 21 paper

README.md

@@ -5,6 +5,27 @@ Vortex is a full-stack open-source RISC-V GPGPU. Vortex supports multiple *backe
 ## Website
 Vortex news can be found on its [website](https://vortex.cc.gatech.edu/)
 
+## Citation
+```
+@inproceedings{10.1145/3466752.3480128,
+	author = {Tine, Blaise and Yalamarthy, Krishna Praveen and Elsabbagh, Fares and Hyesoon, Kim},
+	title = {Vortex: Extending the RISC-V ISA for GPGPU and 3D-Graphics},
+	year = {2021},
+	isbn = {9781450385572},
+	publisher = {Association for Computing Machinery},
+	address = {New York, NY, USA},
+	url = {https://doi.org/10.1145/3466752.3480128},
+	doi = {10.1145/3466752.3480128},
+	abstract = {The importance of open-source hardware and software has been increasing. However, despite GPUs being one of the more popular accelerators across various applications, there is very little open-source GPU infrastructure in the public domain. We argue that one of the reasons for the lack of open-source infrastructure for GPUs is rooted in the complexity of their ISA and software stacks. In this work, we first propose an ISA extension to RISC-V that supports GPGPUs and graphics. The main goal of the ISA extension proposal is to minimize the ISA changes so that the corresponding changes to the open-source ecosystem are also minimal, which makes for a sustainable development ecosystem. To demonstrate the feasibility of the minimally extended RISC-V ISA, we implemented the complete software and hardware stacks of Vortex on FPGA. Vortex is a PCIe-based soft GPU that supports OpenCL and OpenGL. Vortex can be used in a variety of applications, including machine learning, graph analytics, and graphics rendering. Vortex can scale up to 32 cores on an Altera Stratix 10 FPGA, delivering a peak performance of 25.6 GFlops at 200 Mhz.},
+	booktitle = {MICRO-54: 54th Annual IEEE/ACM International Symposium on Microarchitecture},
+	pages = {754–766},
+	numpages = {13},
+	keywords = {reconfigurable computing, memory systems., computer graphics},
+	location = {Virtual Event, Greece},
+	series = {MICRO '21}
+}
+```
+
 ## Specifications
 
 - Support RISC-V RV32IMAF and RV64IMAFD