Add citation info

Author: jonnor

CITATION.cff

@@ -0,0 +1,12 @@
+cff-version: 1.2.0
+license: MIT
+message: "If you use this software, please cite it using these metadata."
+repository-code: "https://github.com/emlearn/emlearn-micropython"
+title: "emlearn-micropython: Efficient Machine Learning engine for MicroPython"
+identifiers:
+  - description: "Archived software version"
+    type: doi
+    value: 10.5281/zenodo.8212731
+authors:
+  - family-names: Nordby
+    given-names: Jon

README.md

@@ -132,3 +132,20 @@ mpremote cp emltrees/emltrees.mpy :emltrees.mpy
 
 `TODO: implement and document`
 
+
+
+## Citations
+
+If you use `emlearn-micropython` in an academic work, please reference it using:
+
+```tex
+@misc{emlearn_micropython,
+  author       = {Jon Nordby},
+  title        = {{emlearn-micropython: Efficient Machine Learning engine for MicroPython}},
+  month        = aug,
+  year         = 2023,
+  doi          = {10.5281/zenodo.8212731},
+  url          = {https://doi.org/10.5281/zenodo.8212731}
+}
+```
+