Print template path chain in TemplateNotFound exceptions (#11886)

Co-authored-by: Adam Turner <[email protected]>

Author: cmarqu

CHANGES.rst

@@ -63,6 +63,8 @@ Bugs fixed
   Patch by James Addison.
 * #11874: Configure a default 30-second value for ``linkcheck_timeout``.
   Patch by James Addison.
+* #11886: Print the Jinja2 template path chain in ``TemplateNotFound`` exceptions.
+  Patch by Colin Marquardt.
 
 Testing
 -------

sphinx/jinja2glue.py

@@ -218,4 +218,5 @@ def get_source(self, environment: Environment, template: str) -> tuple[str, str,
                 return loader.get_source(environment, template)
             except TemplateNotFound:
                 pass
-        raise TemplateNotFound(template)
+        msg = f"{template!r} not found in {self.environment.loader.pathchain}"
+        raise TemplateNotFound(msg)