adding intro to Mide's Get started

Author: EmpieichO

docs/miden/get-started/index.md

@@ -1 +1,5 @@
-This documentation section is under development.
+The Polygon Miden documentation starts with the Miden playground, which is an UI where users can run computations, create proofs of correctness and verify the proofs. The computations include addition of numbers, and finding the n-th member of the Fibonacci sequence.
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+Although it is still WIP, the second section of this documentation provides a brief description of the status of the Polygon Miden zk-rollup, the design approach, as well as its intended benefits to Ethereum.
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+The third section of the Polygon Miden documentation presents the Polygon Miden virtual machine (VM). It provides details on the architecture, network design, project roadmap, and concludes with a subsection on cryptographic primitives. In particular, a delineation of Tiered Sparse Merkle trees.