add: known issues readme

README.md

@@ -3,13 +3,12 @@
 - python 3.7
 - postgresql 12
 
-### Database schema
-includes GIN index column `geodata_search_idx`
-```sql
-ALTER TABLE geodata ADD COLUMN geodata_search_ts TSVECTOR
-GENERATED ALWAYS AS (to_tsvector('russian', geodata.description) STORED
-```
-(use coalese() if multiple)
-```sql
-CREATE INDEX geodata_search_idx ON geodata USING GIN (geodata_search_ts);
+# Known issues
+- ```
+ERROR:  duplicate key value violates unique constraint "pg_type_typname_nsp_index"
+DETAIL:  Key (typname, typnamespace)=(headers, 2200) already exists.
 ```
+at the first database init.
+https://www.postgresql.org/message-id/28194.1101582367%40sss.pgh.pa.us
+Simple restart seems to fix it.
+Use of Alembic might help