fix: fix sharded_tables and refactor omnisharded tables out

docs/configuration/pgdog.toml/omnisharded_tables.md

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+---
+icon: material/content-copy
+---
+
+# Omnisharded tables
+
+[Omnisharded](../../features/sharding/omnishards.md) tables are tables that have the same data on all shards. They typically are small and contain metadata, e.g., list of countries, cities, etc., and are used in joins.
+
+PgDog allows to read from these tables directly and load balances traffic evenly across all shards.
+
+## Configuration
+
+By default, all tables unless otherwise configured as [sharded](sharded_tables.md), are considered omnisharded.
+
+### Sticky routing
+
+Sticky routing disables round robin for omnisharded tables and sends the queries touching those tables to the same shard, guaranteeing consistent results for the duration of a client's connection:
+
+=== "pgdog.toml"
+
+    ```toml
+    [[omnisharded_tables]]
+    database = "prod"
+    sticky = true
+    tables = [
+        "settings",
+        "cities",
+        "terms_of_service",
+        "ip_blocks",
+    ]
+    ```
+
+=== "Helm chart"
+
+    ```yaml
+    omnishardedTables:
+      - database: prod
+        sticky: true
+        tables:
+          - settings
+          - cities
+          - terms_of_service
+          - ip_blocks
+    ```
+
+All queries referencing only these tables will be sent to one of the shards, using the round robin algorithm. If the query contains a sharding key, it will be used instead and omnisharded tables will be ignored by the query router.
+
+#### Default setting
+
+If you want all your omnisharded tables to use sticky routing, you can enable this in the config like so:
+
+```toml
+[general]
+omnisharded_sticky = true
+```
+
+!!! note "Sticky algorithm"
+
+    Routing stickiness is using a random number generator for each connected client.
+    This means different clients will use different shards for the omnisharded table queries, evenly spreading the load across the cluster.
+
+### System catalogs
+
+System tables, like `pg_class`, `pg_database`, and others are expected to be roughly the same on all shards. They may not have the same OIDs for custom data types, but they will for all others.
+
+To make tooling like `psql`, pgAdmin, and others work out of the box, all system catalog tables are automatically omnisharded and sticky.
+
+This can be disabled with configuration:
+
+```toml
+[general]
+system_catalogs = "sharded" # omnishraded_sticky (default), omnisharded
+```