Add guideline about "reviewing doc changes"

Author: GuillaumeGomez

src/SUMMARY.md

@@ -49,6 +49,7 @@
     - [doc alias policy](./documentation/doc-alias-policy.md)
     - [safety comments policy](./documentation/safety-comments.md)
     - [how to write documentation](./how-to-write-documentation.md)
+    - [reviewing doc changes](./reviewing-doc-changes.md)
 
 ---
 

src/documentation/reviewing-doc-changes.md

@@ -0,0 +1,24 @@
+# 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 and needs to go through the
+[libs API team FCP](https://rustc-dev-guide.rust-lang.org/stabilization_guide.html?highlight=fcp#fcp).
+
+It can be circumvented by adding a `# Current Implementation` section
+[like done here](https://github.com/rust-lang/rust/blob/4a8d2e3856c0c75c71998b6c85937203839b946d/library/alloc/src/slice.rs#L250).

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)