Update config, add docs

dendrite-sample.monolith.yaml

@@ -234,6 +234,10 @@ sync_api:
   # address of the client. This is likely required if Dendrite is running behind
   # a reverse proxy server.
   # real_ip_header: X-Real-IP
+  fulltext:
+    enabled: false
+    index_path: "./fulltextindex"
+    language: "en" # more possible languages can be found at https://github.com/blevesearch/bleve/tree/master/analysis/lang
 
 # Configuration for the User API.
 user_api:

dendrite-sample.polylith.yaml

@@ -292,6 +292,10 @@ sync_api:
     max_open_conns: 10
     max_idle_conns: 2
     conn_max_lifetime: -1
+  fulltext:
+    enabled: false
+    index_path: "./fulltextindex"
+    language: "en" # more possible languages can be found at https://github.com/blevesearch/bleve/tree/master/analysis/lang
 
   # This option controls which HTTP header to inspect to find the real remote IP
   # address of the client. This is likely required if Dendrite is running behind

docs/installation/7_configuration.md

@@ -138,6 +138,19 @@ room_server:
     conn_max_lifetime: -1
 ```
 
+## Fulltext search
+
+Dendrite supports experimental fulltext indexing using [Bleve](https://github.com/blevesearch/bleve), it is configured in the `sync_api` section as follows. Depending on the language most likely to be used on the server, it might make sense to change the `language` used when indexing, to ensure the returned results match the expections. A full list of possible languages can be found [here](https://github.com/blevesearch/bleve/tree/master/analysis/lang).
+
+```yaml
+sync_api:
+  # ...
+  fulltext:
+    enabled: false
+    index_path: "./fulltextindex"
+    language: "en"
+```
+
 ## Other sections
 
 There are other options which may be useful so review them all. In particular, if you are