moved `wotb` crate in workspace

.gitignore

+/target/
+\.vscode/
+
+**/*.rs.bk
+Cargo.lock
+*.wot

Cargo.toml

+[workspace]
+members = [
+    "wotb"
+]
\ No newline at end of file

wotb/Cargo.toml

+[package]
+name = "duniter-wotb"
+version = "0.3.2"
+authors = ["nanocryk <nanocryk@duniter.org>"]
+description = "Makes Web of Trust computations for the Duniter project."
+repository = "https://github.com/duniter-rs/wotb"
+readme = "README.md"
+keywords = ["duniter", "wot", "wotb", "web", "trust"]
+license = "GPL-3.0"
+
+[dependencies]
+serde = "1.0.19"
+bincode = "0.9.2"
+serde_derive = "1.0.19"
\ No newline at end of file

wotb/README.md

+# Introduction
+
+`wotb` is a crate making "Web of Trust" computations for
+the [Duniter] project.
+
+[Duniter]: https://duniter.org/en/
+
+# How to use it ?
+
+You can add `duniter-wotb` as a `cargo` dependency in your Rust project.
+To use it in JavaScript, see `duniter-wotb-js` package. (not done yet)
\ No newline at end of file