Add rig-simple example - Rust translation of langchain-simple using r…#2

AlexMikhalev wants to merge 1 commit intomainterraphim/try-coagent:mainfrom

claude/translate-langchain-example-rust-011CUpnqcWeFsTdYFpoBYstAterraphim/try-coagent:claude/translate-langchain-example-rust-011CUpnqcWeFsTdYFpoBYstACopy head branch name to clipboard