Move README.md to connect/README.md

Cargo had a hard time packaging it since it lived outside of the crate's
root directory. I've also created a symbolic link to it at the project's
root to keep GH home page informative.

Author: erickpintor

README.md

@@ -0,0 +1 @@
+connect/README.md

README.md

@@ -1,6 +1,6 @@
 [package]
 name   = "quint-connect"
-readme = "../README.md"
+readme = "README.md"
 description = "A model-based testing framework that connects Quint specifications with Rust applications"
 
 version       = { workspace = true }