Alt text is not descriptive [Build UI pages]

**Describe the content issue**:
Images listed below do not have descriptive/informative alt text. For markdown the alt text is located between the square brackets, ``.

The list below isn't exhaustive since I found these images based on the word count for the alt text, but it should be a good starting point to make our alt text better for people who use screen readers.

Some resources to help write alt text:
- https://webaim.org/techniques/alttext/
- https://www.a11yproject.com/posts/are-you-making-these-five-mistakes-when-writing-alt-text/

 

https://github.com/aws-amplify/docs/blob/main/src/pages/[platform]/build-ui/uibuilder/index.mdx:
```
130 1. Duplicate the new [Figma community file](https://www.figma.com/community/file/1047600760128127424) into your Figma account.
131: 
132 1. In the _new_ Figma file, open the AWS Amplify UI Builder Figma plugin. Navigate to the **Theme presets/Import** tab. Click in the paste your theme input and paste (ctrl/cmd + v). This should update the new file with your theme.

153 * Add TextAreaField primitive component. You can change any existing TextField into a TextAreaField by selecting the desired TextField instance and choosing "TextAreaField" under the Swap Instance dropdown.
154: 
155
```

 

https://github.com/aws-amplify/docs/blob/main/src/pages/[platform]/build-ui/uibuilder/collections/index.mdx:
```
66
67: 
68

72
73: 
74

84
85: 
86

90
91: 
92

105
106: 
107

111
112: 
113
```

 

https://github.com/aws-amplify/docs/blob/main/src/pages/[platform]/build-ui/uibuilder/databinding/index.mdx:
```
41
42: 
43

64 1. **Edit component in Figma**: This will deep link you into the Figma file to edit the component.
65: 2. **Shuffle preview data**: When you bind UI to static data or data from data models, use shuffle preview to see how your component renders with different data. 
66 3. **Create collection**: Create a collection out of a component. [Learn more](/[platform]/build-ui/uibuilder/collections/).

96
97: 
98

102
103: 
104

112
113: 
114

118
119: 
```

 

https://github.com/aws-amplify/docs/blob/main/src/pages/[platform]/build-ui/uibuilder/eventhandling/index.mdx:
```
56 |-|-|
57: | | |
58
```

 

https://github.com/aws-amplify/docs/blob/main/src/pages/[platform]/build-ui/uibuilder/override/index.mdx:
```
270
271: 
272
```

 

https://github.com/aws-amplify/docs/blob/main/src/pages/[platform]/build-ui/uibuilder/slots/index.mdx:
```
53
54: 1. On the left-hand side, you'll see the elements of your component. Select a Figma **Frame** () within your component.
55
```

 

https://github.com/aws-amplify/docs/blob/main/src/pages/[platform]/build-ui/uibuilder/theming/index.mdx:
```
54
55: 
56

62
63: 
64

83
84: 
85

93
94: 
95

102
103: 
104

112
113: 
114

127
128: 
129
```