Update forms library (part 2) (#2174)

* docs(forms): add more feel properties docs

Related to https://github.com/camunda/team-hto/issues/247

* docs(forms): add feel support for multiselect options

* docs(forms): update phrase for example JSON

---------

Co-authored-by: christinaausley <84338309+christinaausley@users.noreply.github.com>

docs/components/modeler/forms/configuration/forms-config-options.md

@@ -43,6 +43,10 @@ The expected format for the data is an array of options, each defining its label
 }
 ```
 
+### FEEL expressions
+
+The options are populated from a [FEEL expression](../../feel/language-guide/feel-expressions-introduction.md) that returns an array of options. The resulting array must be formatted as described in the [example JSON above](#input-data-driven-by-process-data).
+
 #### Shorthand definitions
 
 If the value and label are equal, shorthand formats may be used instead:

docs/components/modeler/forms/form-element-library/forms-element-library-image.md

@@ -10,7 +10,7 @@ An element allowing the user to display images.
 
 ## Configurable properties
 
-- **Image source**: Specifies the image source via [expression](../../feel/language-guide/feel-expressions-introduction.md) or static value (hyperlink or data URI).
-- **Alternative text**: Provides an alternative text to the image in case it cannot be displayed.
+- **Image source**: Specifies the image source via [expression](../../feel/language-guide/feel-expressions-introduction.md), [templating syntax](../configuration/forms-config-templating-syntax.md) or static value (hyperlink or data URI).
+- **Alternative text**: Provides an alternative text to the image in case it cannot be displayed. Can either be an [expression](../../feel/language-guide/feel-expressions-introduction.md), plain text, or [templating syntax](../configuration/forms-config-templating-syntax.md).
 - **Hide if**: [Expression](../../feel/language-guide/feel-expressions-introduction.md) to hide the image.
 - **Columns**: Space the field will use inside its row. **Auto** means it will automatically adjust to available space in the row. Read more about the underlying grid layout in the [Carbon Grid documentation](https://carbondesignsystem.com/guidelines/2x-grid/overview).

docs/components/modeler/forms/form-element-library/forms-element-library-number.md

@@ -23,11 +23,11 @@ A number field allowing the user to read and edit numeric data.
 - **Serialize to string**: Configures the output format of the datetime value. This enables unlimited precision digits.
 - **Validation**: Given that one of the following properties is set, the form will only submit when the respective condition is fulfilled. Otherwise, a validation error will be displayed.
  - **Required**: Number field must contain a value.
- - **Minimum**: Number field value must be at least `n`.
- - **Maximum**: Number field value must be no larger than `n`.
+ - **Minimum**: Number field value must be at least `n`. Can either be an [expression](../../feel/language-guide/feel-expressions-introduction.md) or a number.
+ - **Maximum**: Number field value must be no larger than `n`. Can either be an [expression](../../feel/language-guide/feel-expressions-introduction.md) or a number.
 - **Appearance**: Changes the visual appearance of the number field.
- - **Prefix**: Adds an appendage before the input.
- - **Suffix**: Adds an appendage after the input.
+ - **Prefix**: Adds an appendage before the input. Can either be an [expression](../../feel/language-guide/feel-expressions-introduction.md), plain text, or [templating syntax](../configuration/forms-config-templating-syntax.md).
+ - **Suffix**: Adds an appendage after the input. Can either be an [expression](../../feel/language-guide/feel-expressions-introduction.md), plain text, or [templating syntax](../configuration/forms-config-templating-syntax.md).
 
 ### Datatypes
 

docs/components/modeler/forms/form-element-library/forms-element-library-textfield.md

@@ -21,12 +21,12 @@ A text field allowing the user to read and edit textual data.
 - **Validation**: Given that one of the following properties is set, the form will only submit when the respective condition is fulfilled. Otherwise, a validation error will be displayed.
  - **Required**: Text field must contain a value.
  - **Regular expression validation**: Use predefined validation patterns. Available options are: `Email`, `Phone`, and `Custom`.
- - **Minimum length**: Text field must have at least `n` characters.
- - **Maximum length**: Text field must not have more than `n` characters.
+ - **Minimum length**: Text field must have at least `n` characters. Can either be an [expression](../../feel/language-guide/feel-expressions-introduction.md) or a number.
+ - **Maximum length**: Text field must not have more than `n` characters. Can either be an [expression](../../feel/language-guide/feel-expressions-introduction.md) or a number.
  - **Regular expression pattern**: Text field value must match the provided [RegEx](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Cheatsheet) pattern.
 - **Appearance**: Changes the visual appearance of the text field.
- - **Prefix**: Adds an appendage before the input.
- - **Suffix**: Adds an appendage after the input.
+ - **Prefix**: Adds an appendage before the input. Can either be an [expression](../../feel/language-guide/feel-expressions-introduction.md), plain text, or [templating syntax](../configuration/forms-config-templating-syntax.md).
+ - **Suffix**: Adds an appendage after the input. Can either be an [expression](../../feel/language-guide/feel-expressions-introduction.md), plain text, or [templating syntax](../configuration/forms-config-templating-syntax.md).
 
 ### Datatypes