Update changelog, and document specparser inheritance behavior

Author: i80and

CHANGELOG.md

@@ -7,6 +7,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- To prepare for updating the version of the parser used by the VSCode extension,
+  the postprocessor has been temporarily disabled in the language server.
+
+### Deprecated
+
+- The following directives are deprecated: `admonition`, `danger`, `caution`, and `topic` (DOP-1243).
+
 ## [v0.5.2] - 2020-07-15
 
 ### Fixed

snooty/specparser.py

@@ -295,7 +295,11 @@ def validator(argument: str) -> object:
         raise ValueError(f'Unknown directive argument type "{option_spec}"')
 
     def _resolve_inheritance(self) -> None:
-        """Directives can inherit from other directives; resolve this."""
+        """Spec entries can inherit from other entries; resolve this.
+
+           Not all fields are implicitly inherited: only fields with a default value
+           of None or MissingDict are inherited. This means that, for example content_type
+           is inherited, but as of this writing, deprecated is not."""
         self._resolve_category(self.directive)
         self._resolve_category(self.role)
         self._resolve_category(self.rstobject)