Improve CHANGELOG.

CHANGELOG.md

@@ -143,15 +143,18 @@ HeapLang, which is now in a separate package `coq-iris-heap-lang`.
   initial heap.
 * Rename `mapsto_mapsto_ne` to `mapsto_frac_ne`, and add a simpler
   `mapsto_ne` that does not require reasoning about fractions.
-* Generalize the `gen_heap` library to discardable fractions.
+* Extend the `gen_heap` library with read-only points-to assertions using
+  [discardable fractions](iris/algebra/dfrac.v).
   + The `mapsto` connective now takes a `dfrac` rather than a `frac` (i.e.,
     positive rational number `Qp`).
   + The notation `l ↦{ dq } v` is generalized to discardable fractions
     `dq : dfrac`.
   + The new notation `l ↦{# q} v` is used for a concrete fraction `q : frac`
     (e.g., to enable writing `l ↦{# 1/2} v`).
-  + The new notation `l ↦□ v` is used for the discarded fraction.
-  + The lemma `mapsto_persist : l ↦{dq} v ==∗ l ↦□ v` has been added.
+  + The new notation `l ↦□ v` is used for the discarded fraction. This
+    persistent proposition provides read-only access to `l`.
+  + The lemma `mapsto_persist : l ↦{dq} v ==∗ l ↦□ v` is used for making the
+    location `l` read-only.
   + See the changes to HeapLang for an indication on how to adapt your language.
   + See the changes to iris-examples for an indication on how to adapt your
     development. In particular, instead of `∃ q, l ↦{q} v` you likely want to
@@ -167,10 +170,9 @@ HeapLang, which is now in a separate package `coq-iris-heap-lang`.
   avoid TC search attempting to apply this instance all the time.
 * Merge `wp_value_inv`/`wp_value_inv'` into `wp_value_fupd`/`wp_value_fupd'` by
   making the lemma bidirectional.
-* Generalize HeapLang's `mapsto` (`↦`) and `array` (`↦∗`) connectives to
-  discardable fractions. See the CHANGELOG entry in the category `base_logic`
-  for more information.
-* Generalize HeapLang's atomic heap to discardable fractions.
+* Generalize HeapLang's `mapsto` (`↦`), `array` (`↦∗`), and atomic heap
+  connectives to discardable fractions. See the CHANGELOG entry in the category
+  `base_logic` for more information.
 
 **Changes in `heap_lang`:**