add better marker description.

Author: tobiasraabe

docs/reference_guides/marks.rst

@@ -32,4 +32,35 @@ pytask.mark.try_first
 .. function:: try_first
     :noindex:
 
-    This
+    Indicate that the task should be executed as soon as possible.
+
+    This indicator is a soft measure to influence the execution order of pytask.
+
+    .. important::
+
+        This indicator is not intended for general use to influence the build order and
+        to overcome misspecification of task dependencies and products.
+
+        It should only be applied to situations where it is hard to define all
+        dependencies and products and automatic inference may be incomplete like with
+        pytask-latex and latex-dependency-scanner.
+
+
+pytask.mark.try_last
+---------------------
+
+.. function:: try_last
+    :noindex:
+
+    Indicate that the task should be executed as late as possible.
+
+    This indicator is a soft measure to influence the execution order of pytask.
+
+    .. important::
+
+        This indicator is not intended for general use to influence the build order and
+        to overcome misspecification of task dependencies and products.
+
+        It should only be applied to situations where it is hard to define all
+        dependencies and products and automatic inference may be incomplete like with
+        pytask-latex and latex-dependency-scanner.