partition: reformat usage text

[skip ci]

src/cmd/partition.rs

@@ -11,23 +11,23 @@ Usage:
  qsv partition --help
 
 partition options:
- --filename <filename> A filename template to use when constructing
- the names of the output files. The string '{}'
- will be replaced by a value based on the value
- of the field, but sanitized for shell safety.
- [default: {}.csv]
+ --filename <filename>  A filename template to use when constructing the
+  names of the output files. The string '{}' will
+  be replaced by a value based on the partition column,
+   but sanitized for shell safety.
+  [default: {}.csv]
  -p, --prefix-length <n> Truncate the partition column after the
- specified number of bytes when creating the
- output file.
- --drop Drop the partition column from results.
+  specified number of bytes when creating the
+  output file.
+ --drop  Drop the partition column from results.
 
 Common options:
- -h, --help Display this message
- -n, --no-headers When set, the first row will NOT be interpreted
- as column names. Otherwise, the first row will
- appear in all chunks as the header row.
- -d, --delimiter <arg> The field delimiter for reading CSV data.
- Must be a single character. (default: ,)
+ -h, --help  Display this message
+ -n, --no-headers  When set, the first row will NOT be interpreted
+  as column names. Otherwise, the first row will
+  appear in all chunks as the header row.
+ -d, --delimiter <arg>  The field delimiter for reading CSV data.
+  Must be a single character. (default: ,)
 "#;
 
 use std::{