Update prometheus dashboard unit format documentation

doc/user/project/integrations/prometheus.md

@@ -296,10 +296,10 @@ The following tables outline the details of expected properties.
 **Axis (`panels[].y_axis`) properties:**
 
 | Property    | Type   | Required                      | Description                                                          |
-| ----------- | ------ | ------------------------- | -------------------------------------------------------------------- |
-| `name`      | string | no, but highly encouraged | Y-Axis label for the panel, it will replace `y_label` if set.        |
-| `format`    | string | no, defaults to `number`  | Unit format used. See the [full list of units](prometheus_units.md). |
-| `precision` | number | no, defaults to `2`       | Number of decimals to display in the number.                         |
+| ----------- | ------ | ----------------------------- | -------------------------------------------------------------------- |
+| `name`      | string | no, but highly encouraged     | Y-Axis label for the panel. Replaces `y_label` if set.               |
+| `format`    | string | no, defaults to `engineering` | Unit format used. See the [full list of units](prometheus_units.md). |
+| `precision` | number | no, defaults to `2`           | Number of decimal places to display in the number.                                          |                        |
 
 **Metrics (`metrics`) properties:**
 

doc/user/project/integrations/prometheus_units.md

@@ -5,16 +5,75 @@
 You can select units to format your charts by adding `format` to your
 [axis configuration](prometheus.md#dashboard-yaml-properties).
 
+## Internationalization and localization
+
+Currently, your [internationalization and localization options](https://en.wikipedia.org/wiki/Internationalization_and_localization) for number formatting are dependent on the system you are using i.e. your OS or browser.
+
+## Engineering Notation
+
+For generic or default data, numbers are formatted according to the current locale in [engineering notation](https://en.wikipedia.org/wiki/Engineering_notation).
+
+While an [engineering notation exists for the web](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/NumberFormat), GitLab uses a version based off the [scientific notation](https://en.wikipedia.org/wiki/Scientific_notation). GitLab formatting acts in accordance with SI prefixes. For example, using GitLab notation, `1500.00` becomes `1.5k` instead of `1.5E3`. Keep this distinction in mind when using the engineering notation for your metrics.
+
+Formats: `engineering`
+
+SI prefixes:
+
+| Name       | Symbol  | Value                      |
+| ---------- | ------- | -------------------------- |
+| `yotta`    | Y       | 1000000000000000000000000  |
+| `zetta`    | Z       | 1000000000000000000000     |
+| `exa`      | E       | 1000000000000000000        |
+| `peta`     | P       | 1000000000000000           |
+| `tera`     | T       | 1000000000000              |
+| `giga`     | G       | 1000000000                 |
+| `mega`     | M       | 1000000                    |
+| `kilo`     | k       | 1000                       |
+| `milli`    | m       | 0.001                      |
+| `micro`    | μ       | 0.000001                   |
+| `nano`     | n       | 0.000000001                |
+| `pico`     | p       | 0.000000000001             |
+| `femto`    | f       | 0.000000000000001          |
+| `atto`     | a       | 0.000000000000000001       |
+| `zepto`    | z       | 0.000000000000000000001    |
+| `yocto`    | y       | 0.000000000000000000000001 |
+
+**Examples:**
+
+| Data                              | Displayed |
+| --------------------------------- | --------- |
+| `0.000000000000000000000008`      | 8y        |
+| `0.000000000000000000008`         | 8z        |
+| `0.000000000000000008`            | 8a        |
+| `0.000000000000008`               | 8f        |
+| `0.000000000008`                  | 8p        |
+| `0.000000008`                     | 8n        |
+| `0.000008`                        | 8μ        |
+| `0.008`                           | 8m        |
+| `10`                              | 10        |
+| `1080`                            | 1.08k     |
+| `18000`                           | 18k       |
+| `18888`                           | 18.9k     |
+| `188888`                          | 189k      |
+| `18888888`                        | 18.9M     |
+| `1888888888`                      | 1.89G     |
+| `1888888888888`                   | 1.89T     |
+| `1888888888888888`                | 1.89P     |
+| `1888888888888888888`             | 1.89E     |
+| `1888888888888888888888`          | 1.89Z     |
+| `1888888888888888888888888`       | 1.89Y     |
+| `1888888888888888888888888888`    | 1.89e+27  |
+
 ## Numbers
 
-For generic data, numbers are formatted according to the current locale.
+For number data, numbers are formatted according to the current locale.
 
 Formats: `number`
 
 **Examples:**
 
 | Data  | Displayed |
-| --------- | --------- |
+| ---------- | --------- |
 | `10`       | 1         |
 | `1000`     | 1,000     |
 | `1000000`  | 1,000,000 |