Document code maintenance procedure

diff --git a/README.md b/README.md
index 4b200bf9dbd0cc6ba3945c0a235ae370a277d3e3..44dfc60ec1565f00722b1ef3684749086de43804 100644 (file)
--- a/README.md
+++ b/README.md
@@ -16,3 +16,9 @@ as
 [described in the readme](https://www.dealii.org/developer/readme.html#documentation).
 It will pick up the code gallery and create joint documentation for the
 tutorial and the code gallery.
+
+### Maintainance of contributed codes
+
+The examples in the code-gallery of periodically adjusted so that they maintain compatibility with a "recent" version of the `deal.II`. This means that their implementation may be modified slightly in the process, breaking compatibility with older versions of `deal.II`. Older version of each contributed code may be attained by checking out the appropriate git commit of the code-gallery repository.
+
+The minimum required version of `deal.II` for all code-gallery examples is `9.1`.