Small docs fixes (#757)

* update router config docs

* update ALTER DISTRIBUTION syntax in docs

* fix internal link

* update get_started

docs/configuration/router.mdx

@@ -83,11 +83,13 @@ Map of string to Shard objects. Refer to the `Shard` struct in the [pkg/config/r
 
 ## Feature Flags
 
-| Setting                  | Description                                   | Possible Values |
-|--------------------------|-----------------------------------------------|-----------------|
-| `maintain_params`        | Whether to maintain parameters flag.          | `true`, `false` |
-| `with_jaeger`            | Whether to integrate with Jaeger for tracing. | `true`, `false` |
-| `world_shard_fallback`   | Whether to enable fallback to world shard.    | `true`, `false` |
+| Setting                                 | Description                                     | Possible Values |
+|-----------------------------------------|-------------------------------------------------|-----------------|
+| `maintain_params`                       | Whether to maintain parameters flag.            | `true`, `false` |
+| `query_routing.default_route_behaviour` | Whether to explicitly block multishard queries. | `BLOCK`, ``     |
+| `query_routing.multicast_unroutable_insert_statement` | Whether to send insert statements without a sharding key to all shards. | `true`, `false` |
+| `with_jaeger`                           | Whether to integrate with Jaeger for tracing.   | `true`, `false` |
+| `world_shard_fallback`                  | Whether to enable fallback to world shard.      | `true`, `false` |
 
 
 ## Mode Settings

docs/sharding/console/sql_commands.mdx

@@ -8,7 +8,7 @@ Description: 'Create distributions, key ranges and tables and see cluster info'
 This command is used to create a new distribution with the specified name. Optionally, you can specify the column types for the distribution using the COLUMN TYPES clause.
 
 ```sql
-CREATE DISTRIBUTION <distributionID> [COLUMN TYPES types]
+CREATE DISTRIBUTION <distributionID> COLUMN TYPES <types>
 
 where types is a comma-separated list of column types
 
@@ -23,16 +23,23 @@ This command is used to drop an existing distribution with the specified name. T
 DROP DISTRIBUTION <distribution_name> [CASCADE]
 ```
 
-### ALTER DISTRIBUTION
+### ALTER DISTRIBUTION ATTACH RELATION
 
-This command is used to alter an existing distribution. You can attach one or more relations to the distribution using the ATTACH RELATION clause, or detach a relation from the distribution using the DETACH RELATION clause.
+This command is used to alter an existing distribution. You can attach one or more relations to the distribution using the ATTACH RELATION clause.
 
 ```sql
-ALTER DISTRIBUTION <distribution_name> 
-[
-    ATTACH RELATION <relation_name> [, <relation_name> ...] | 
-    DETACH RELATION <relation_name>
-]
+ALTER DISTRIBUTION <distribution_name> ATTACH RELATION <relation_name> [, <relation_name> ...] 
+DISTRIBUTION KEY <keys> [HASH FUNCTION <hash_function_name>]
+
+where hash_function_name is one of: IDENTITY, MURMUR, CITY
+```
+
+### ALTER DISTRIBUTION DETACH RELATION
+
+This command is used to alter an existing distribution. You can detach a relation from the distribution using the DETACH RELATION clause.
+
+```sql
+ALTER DISTRIBUTION <distribution_name> DETACH RELATION <relation_name>
 ```
 
 ### CREATE KEY RANGE

docs/welcome/get_started.mdx

@@ -93,4 +93,62 @@ CREATE KEY RANGE krid2 FROM 1000 ROUTE TO shard2 FOR DISTRIBUTION ds1;
 (1 row)
 ```
 
-Here we go! You can play with some SELECTs or INSERTs.
+Here we go! You can play with some SELECTs or INSERTs.
+
+### Connect to SPQR router
+
+Now we can connect to proxy a.k.a. router and play with it:
+
+```bash
+➜ psql "host=localhost sslmode=disable user=demo dbname=demo port=6432"
+psql (13.3, server 9.6.22)
+Type "help" for help.
+
+demo=> CREATE TABLE orders (
+    id SERIAL NOT NULL PRIMARY KEY,
+    customer_id INT,
+    order_date DATE
+);
+NOTICE: send query to shard(s) : shard01,shard02
+CREATE TABLE
+
+demo=> CREATE TABLE items (
+    id SERIAL NOT NULL PRIMARY KEY,
+    order_id SERIAL NOT NULL PRIMARY KEY,
+    name VARCHAR,
+);
+NOTICE: send query to shard(s) : shard01,shard02
+CREATE TABLE
+
+demo=> BEGIN;
+BEGIN
+demo=> INSERT INTO orders (id, customer_id, order_data) VALUES (777, 123456, '2024-01-08');
+NOTICE: send query to shard(s) : shard01
+INSERT 0 1
+demo=> INSERT INTO items (id, order_id, name) VALUES (1, 777, 'elephant');
+INSERT 0 1
+demo=> COMMIT;
+COMMIT
+```
+
+> NOTICE messages are disabled by default, specify `show_notice_messages` setting in the router config to enable them
+
+You could check now that each shard has only one record:
+
+```bash
+demo=> SELECT * FROM orders WHERE id = 777;
+NOTICE: send query to shard(s) : shard01
+  id  | customer_id | order_data 
+------+-------------+--------------
+  777 |   123456    | '2024-01-08'
+(1 row)
+
+SPQR can handle such queries as `SELECT * FROM table` but we don't recommend using it. This feature is implemented in a non-transactional way.
+
+```bash
+demo=> SELECT * FROM orders WHERE id = 777;
+NOTICE: send query to shard(s) : shard01
+  id  | customer_id | order_data 
+------+-------------+--------------
+  777 |   123456    | '2024-01-08'
+(1 row)

docs/welcome/index.mdx

@@ -32,7 +32,7 @@ SPQR is a good fit for:
   <Card
     title="Internals"
     icon="code"
-    href="/internals/balancing"
+    href="/sharding/cluster_components/overview"
   >
     Learn more how SPQR works under the hood
   </Card>