fix: refine mermaid diagram style

crates/loro-core/src/dag.rs

@@ -192,6 +192,8 @@ pub(crate) trait Dag {
         iter_dag(self)
     }
 
+    /// You can visualize and generate img link at https://mermaid.live/
+    #[inline]
     fn mermaid(&self) -> String
     where
         Self: Sized,

crates/loro-core/src/dag/mermaid.rs

@@ -43,8 +43,12 @@ fn to_str(output: Output) -> String {
 
             is_first = false;
             s += format!(
-                "{}-{}(ctr: {}..{})",
-                id_span.client_id, id_span.counter.from, id_span.counter.from, id_span.counter.to
+                "{}-{}(\"c{}: [{}, {})\")",
+                id_span.client_id,
+                id_span.counter.from,
+                id_span.client_id,
+                id_span.counter.from,
+                id_span.counter.to
             )
             .as_str();
         }

crates/loro-core/src/dag/test.rs

@@ -473,7 +473,7 @@ mod find_common_ancestors {
         );
     }
 
-    /// ![](https://i.ibb.co/C5xLG53/image.png)
+    /// ![](https://mermaid.ink/img/pako:eNqNkTFPwzAQhf_K6SYqOZJ9CYsHJroxwYgXY7skInEq1xFCVf87jg5XVQQSnk6fz_feO5_RzT6gxsM4f7repgzPTyZCOafl7T3ZYw9uHELMkqls2juDTmp4bQV0O4M7aJqHwqlyEtDecFW5EkA3XFYuBaiVs0CInotfXSimqunW16q87gTcX6cqdqe27hSrKVZr_6tGTImn0nYqcWbaZiZWI1ajP9WK2zqnClFd5jVn3SIKnEKa7ODLb53Xa4O5D1MwqEvpbfowaOKl9C1Hb3PY-yHPCfXBjqcg0C55fvmKDnVOS6hNj4Mtgaefrss3dp6HFg)
     #[test]
     fn large_lamport_with_longer_path() {
         let mut a0 = TestDag::new(0);