Add guideline about "reviewing doc changes"

Author: GuillaumeGomez

src/documentation/reviewing-doc-changes.md

@@ -0,0 +1,19 @@
+# Reviewing doc changes
+
+Most of the time, it is mostly reviewing that the documentation isn't wrong
+in any way and that it follows the
+[how to write documentation](./how-to-write-documentation.md) guideline.
+
+There is however something where we need to be extra careful: stability
+guarantees.
+
+## Stability guarantees
+
+First, short explanation about what a stability guarantee is: a statement in
+the document which explains what the item is doing in a precise case. For
+example:
+ * Showing precisely how a function on floats handles `NaN`.
+ * Saying that a sort method has a particular running-time bound.
+
+So if a doc change updates/adds/removes a stability guarantee, it has to be
+**very** carefully handled!

src/documentation/summary.md

@@ -1,3 +1,4 @@
 - [doc alias policy](./doc-alias-policy.md)
 - [safety comments policy](./safety-comments.md)
 - [how to write documentation](./how-to-write-documentation.md)
+- [reviewing doc changes](./reviewing-doc-changes.md)