docs(readme): Add short_numbers docs

Author: DenverCoder1

README.md

@@ -68,6 +68,7 @@ If the `theme` parameter is specified, any color customizations specified will b
 |     `excludeDaysLabel`     |       Excluded days of the week text color       |                             **hex code** without `#` or **css color**                              |
 |       `date_format`        |  Date format pattern or empty for locale format  |                        See note below on [📅 Date Formats](#-date-formats)                         |
 |          `locale`          |  Locale for labels and numbers (Default: `en`)   |                            ISO 639-1 code - See [🗪 Locales](#-locales)                             |
+|      `short_numbers`       |  Use short numbers (e.g. 1.5k instead of 1,500)  |                                         `true` or `false`                                          |
 |           `type`           |          Output format (Default: `svg`)          |                              Current options: `svg`, `png` or `json`                               |
 |           `mode`           |          Streak mode (Default: `daily`)          |             `daily` (contribute daily) or `weekly` (contribute once per Sun-Sat week)              |
 |       `exclude_days`       | List of days of the week to exclude from streaks |    Comma-separated list of day abbreviations (Sun, Mon, Tue, Wed, Thu, Fri, Sat) e.g. `Sun,Sat`    |