Machine-readable config description

changelog.d/17892.doc

@@ -0,0 +1 @@
+Generate config documentation from JSON Schema file.

docs/usage/administration/admin_faq.md

@@ -255,7 +255,7 @@ line to `/etc/default/matrix-synapse`:
 
     LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.2
 
-*Note*: You may need to set `PYTHONMALLOC=malloc` to ensure that `jemalloc` can accurately calculate memory usage. By default, Python uses its internal small-object allocator, which may interfere with jemalloc's ability to track memory consumption correctly. This could prevent the [cache_autotuning](../configuration/config_documentation.md#caches-and-associated-values) feature from functioning as expected, as the Python allocator may not reach the memory threshold set by `max_cache_memory_usage`, thus not triggering the cache eviction process.
+*Note*: You may need to set `PYTHONMALLOC=malloc` to ensure that `jemalloc` can accurately calculate memory usage. By default, Python uses its internal small-object allocator, which may interfere with jemalloc's ability to track memory consumption correctly. This could prevent the [cache_autotuning](../configuration/config_documentation.md#caches) feature from functioning as expected, as the Python allocator may not reach the memory threshold set by `max_cache_memory_usage`, thus not triggering the cache eviction process.
 
 This made a significant difference on Python 2.7 - it's unclear how
 much of an improvement it provides on Python 3.x.

schema/meta.schema.json

@@ -0,0 +1,29 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://schema.element.io/v1/meta.schema.json",
+  "$vocabulary": {
+    "https://json-schema.org/draft/2020-12/vocab/core": true,
+    "https://json-schema.org/draft/2020-12/vocab/applicator": true,
+    "https://json-schema.org/draft/2020-12/vocab/unevaluated": true,
+    "https://json-schema.org/draft/2020-12/vocab/validation": true,
+    "https://json-schema.org/draft/2020-12/vocab/meta-data": true,
+    "https://json-schema.org/draft/2020-12/vocab/format-annotation": true,
+    "https://json-schema.org/draft/2020-12/vocab/content": true,
+    "https://schema.element.io/v1/vocab/documentation": true
+  },
+  "$ref": "https://json-schema.org/draft/2020-12/schema",
+  "properties": {
+    "io.element.type_name": {
+      "type": "string",
+      "description": "Human-readable type of a schema that is displayed instead of the standard JSON Schema types like `object` or `integer`. In case the JSON Schema type contains `null`, this information should be presented alongside the human-readable type name.",
+      "examples": ["duration", "byte size"]
+    },
+    "io.element.post_description": {
+      "type": "string",
+      "description": "Additional description of a schema, better suited to be placed less prominently in the generated documentation, e.g., at the end of a section after listings of items and properties.",
+      "examples": [
+        "### Advanced uses\n\nThe spent coffee grounds can be added to compost for improving soil and growing plants."
+      ]
+    }
+  }
+}