add PARTITION BY to s3 and hdfs docs

docs/en/engines/table-engines/integrations/hdfs.md

@@ -21,6 +21,13 @@ ENGINE = HDFS(URI, format)
 `SELECT` queries, the format must be supported for input, and to perform
 `INSERT` queries – for output. The available formats are listed in the
 [Formats](../../../interfaces/formats.md#formats) section.
+- [PARTITION BY expr]
+
+### PARTITION BY
+
+`PARTITION BY` — Optional. In most cases you don't need a partition key, and if it is needed you generally don't need a partition key more granular than by month. Partitioning does not speed up queries (in contrast to the ORDER BY expression). You should never use too granular partitioning. Don't partition your data by client identifiers or names (instead, make client identifier or name the first column in the ORDER BY expression).
+
+For partitioning by month, use the `toYYYYMM(date_column)` expression, where `date_column` is a column with a date of the type [Date](/docs/en/sql-reference/data-types/date.md). The partition names here have the `"YYYYMM"` format.
 
 **Example:**
 

docs/en/engines/table-engines/integrations/s3.md

@@ -13,6 +13,7 @@ This engine provides integration with [Amazon S3](https://aws.amazon.com/s3/) ec
 ``` sql
 CREATE TABLE s3_engine_table (name String, value UInt32)
     ENGINE = S3(path, [aws_access_key_id, aws_secret_access_key,] format, [compression])
+    [PARTITION BY expr]
     [SETTINGS ...]
 ```
 
@@ -23,6 +24,12 @@ CREATE TABLE s3_engine_table (name String, value UInt32)
 -   `aws_access_key_id`, `aws_secret_access_key` - Long-term credentials for the [AWS](https://aws.amazon.com/) account user.  You can use these to authenticate your requests. Parameter is optional. If credentials are not specified, they are used from the configuration file. For more information see [Using S3 for Data Storage](../mergetree-family/mergetree.md#table_engine-mergetree-s3).
 -   `compression` — Compression type. Supported values: `none`, `gzip/gz`, `brotli/br`, `xz/LZMA`, `zstd/zst`. Parameter is optional. By default, it will autodetect compression by file extension.
 
+### PARTITION BY
+
+`PARTITION BY` — Optional. In most cases you don't need a partition key, and if it is needed you generally don't need a partition key more granular than by month. Partitioning does not speed up queries (in contrast to the ORDER BY expression). You should never use too granular partitioning. Don't partition your data by client identifiers or names (instead, make client identifier or name the first column in the ORDER BY expression).
+
+For partitioning by month, use the `toYYYYMM(date_column)` expression, where `date_column` is a column with a date of the type [Date](/docs/en/sql-reference/data-types/date.md). The partition names here have the `"YYYYMM"` format.
+
 **Example**
 
 ``` sql

docs/en/engines/table-engines/mergetree-family/mergetree.md

@@ -77,7 +77,7 @@ Use the `ORDER BY tuple()` syntax, if you do not need sorting. See [Selecting th
 
 #### PARTITION BY
 
-`PARTITION BY` — The [partitioning key](/docs/en/engines/table-engines/mergetree-family/custom-partitioning-key.md). Optional. In most cases you don't need partition key, and in most other cases you don't need partition key more granular than by months. Partitioning does not speed up queries (in contrast to the ORDER BY expression). You should never use too granular partitioning. Don't partition your data by client identifiers or names (instead make client identifier or name the first column in the ORDER BY expression).
+`PARTITION BY` — The [partitioning key](/docs/en/engines/table-engines/mergetree-family/custom-partitioning-key.md). Optional. In most cases, you don't need a partition key, and if you do need to partition, generally you do not need a partition key more granular than by month. Partitioning does not speed up queries (in contrast to the ORDER BY expression). You should never use too granular partitioning. Don't partition your data by client identifiers or names (instead, make client identifier or name the first column in the ORDER BY expression).
 
 For partitioning by month, use the `toYYYYMM(date_column)` expression, where `date_column` is a column with a date of the type [Date](/docs/en/sql-reference/data-types/date.md). The partition names here have the `"YYYYMM"` format.