docs: show binding name for `No documentation found for ...` message (#57093)
Making it more informative.
E.g., the difference for `help?> Base._wait` is:
```diff
diff --git a/old b/new
index 87f9b2d43a..5fb065658a 100644
--- a/old
+++ b/new
@@ -5,7 +5,7 @@
│
│ • `Base._wait`
- No documentation found for private symbol.
+ No documentation found for private binding `Base._wait`.
`Base._wait` is a `Function`.
```