do an actual link to detect if it breaks in future (#1517)

Co-authored-by: Noah Lev <camelidcamel@gmail.com>

Author: tshepang

src/queries/incremental-compilation-in-detail.md

@@ -175,19 +175,19 @@ fn try_mark_green(tcx, current_node) -> bool {
 
     true
 }
-
-// Note: The actual implementation can be found in
-//       compiler/rustc_query_system/src/dep_graph/graph.rs
 ```
 
+> NOTE:
+> The actual implementation can be found in
+> [`compiler/rustc_query_system/src/dep_graph/graph.rs`][try_mark_green]
+
 By using red-green marking we can avoid the devastating cumulative effect of
 having false positives during change detection. Whenever a query is executed
 in incremental mode, we first check if its already green. If not, we run
 `try_mark_green()` on it. If it still isn't green after that, then we actually
 invoke the query provider to re-compute the result.
 
 
-
 ## The Real World: How Persistence Makes Everything Complicated
 
 The sections above described the underlying algorithm for incremental
@@ -533,5 +533,5 @@ be reusable. See <https://github.com/rust-lang/rust/issues/47389> for more
 information.
 
 
-
 [query-model]: ./query-evaluation-model-in-detail.html
+[try_mark_green]: https://doc.rust-lang.org/nightly/nightly-rustc/src/rustc_query_system/dep_graph/graph.rs.html