docs: Describe CUBEJS_MAX_SESSIONS environment variable (#8782)

Author: igorlukanin

docs/pages/product/apis-integrations/sql-api.mdx

@@ -211,7 +211,7 @@ error: `Error during rewrite: Can't find rewrite due to 10002 AST node limit rea
 Use the following environment variables to allocate more resources for query planning:
 `CUBESQL_REWRITE_MAX_NODES`, `CUBESQL_REWRITE_MAX_ITERATIONS`, `CUBESQL_REWRITE_TIMEOUT`.
 
-## Streaming
+### Streaming
 
 By default, query results are loaded in a single batch. However, a more effective
 *streaming mode* can be used for large result sets. To enable it, set the
@@ -224,6 +224,14 @@ does not apply to SQL API queries. They can return an unlimited number of rows.
 
 </InfoBox>
 
+### Session limit
+
+Each concurrent connection to the SQL API consumes some resources and attempting
+to establish too many connections at once can lead to an out-of-memory crash.
+You can use the `CUBEJS_MAX_SESSIONS` environment variable to adjust the session
+limit.
+
+
 [ref-sql-api-auth]: /product/apis-integrations/sql-api/security
 [ref-config-checksqlauth]: /reference/configuration/config#checksqlauth
 [ref-config-canswitchsqluser]: /reference/configuration/config#canswitchsqluser

docs/pages/reference/configuration/environment-variables.mdx

@@ -993,7 +993,17 @@ clause](/product/apis-integrations/queries#order) for [SQL API][ref-sql-api] que
 
 | Possible Values | Default in Development | Default in Production |
 | --------------- | ---------------------- | --------------------- |
-| `true`, `false` | `true`                | `true`               |
+| `true`, `false` | `true`                 | `true`                |
+
+## `CUBEJS_MAX_SESSIONS`
+
+Specifies the maximum number of concurrent sessions (connections) to the
+[SQL API][ref-sql-api] and safeguards your Cube deployment from out-of-memory
+crashes when too many connections are attempted to be established.
+
+| Possible Values | Default in Development | Default in Production |
+| --------------- | ---------------------- | --------------------- |
+| A valid number  | 1024                   | 1024                  |
 
 ## `CUBESQL_REWRITE_MAX_NODES`