fix(ui-buttons): address PR review feedback

Remove v1 test files (only latest version needs tests) and simplify
backgroundless button documentation section in v2 Button README.

Author: balzss

packages/ui-buttons/src/BaseButton/v1/__tests__/BaseButton.test.tsx

@@ -24,12 +24,24 @@ type: example
   <Button color="secondary" margin="small">Secondary</Button>
   <Button color="success" margin="small">Success</Button>
   <Button color="danger" margin="small">Danger</Button>
-  <Button color="primary-inverse" margin="small">Primary Inverse</Button>
   <Button color="ai-primary" margin="small">AI Primary</Button>
   <Button color="ai-secondary" margin="small">AI Secondary</Button>
 </View>
 ```
 
+### Primary Inverse
+
+The `primary-inverse` color is designed for use on colored backgrounds. It provides adequate contrast when placed on colored surfaces.
+
+```js
+---
+type: example
+---
+<View display="block" background="brand" padding="small">
+  <Button color="primary-inverse" margin="small">Primary Inverse</Button>
+</View>
+```
+
 ### AI buttons
 
 There is a specific need for `AI buttons`, which has an icon and gradient colors for `background` and `borders`. Here are the preset examples you can use. (the `IconButton` examples are also included for convenience)
@@ -39,12 +51,12 @@ There is a specific need for `AI buttons`, which has an icon and gradient colors
 type: example
 ---
 <View display="block">
-  <Button color="ai-primary" renderIcon={SparklesInstUIIcon} margin="small">AI Primary</Button>
-  <Button color="ai-secondary" renderIcon={SparklesInstUIIcon} margin="small">AI Secondary</Button>
-  <IconButton color="ai-primary" screenReaderLabel="AI button" margin="small"><SparklesInstUIIcon/></IconButton>
-  <IconButton  shape='circle' color="ai-secondary" screenReaderLabel="AI button"  margin="small"><SparklesInstUIIcon/></IconButton>
-  <IconButton   shape='circle' color="ai-primary" screenReaderLabel="AI button" margin="small"><SparklesInstUIIcon/></IconButton>
-  <IconButton color="ai-secondary" screenReaderLabel="AI button"  margin="small"><SparklesInstUIIcon/></IconButton>
+  <Button color="ai-primary" renderIcon={IgniteaiLogoInstUIIcon} margin="small">AI Primary</Button>
+  <Button color="ai-secondary" renderIcon={IgniteaiLogoInstUIIcon} margin="small">AI Secondary</Button>
+  <IconButton color="ai-primary" screenReaderLabel="AI button" margin="small"><IgniteaiLogoInstUIIcon/></IconButton>
+  <IconButton  shape='circle' color="ai-secondary" screenReaderLabel="AI button"  margin="small"><IgniteaiLogoInstUIIcon/></IconButton>
+  <IconButton   shape='circle' color="ai-primary" screenReaderLabel="AI button" margin="small"><IgniteaiLogoInstUIIcon/></IconButton>
+  <IconButton color="ai-secondary" screenReaderLabel="AI button"  margin="small"><IgniteaiLogoInstUIIcon/></IconButton>
 </View>
 ```
 
@@ -72,7 +84,6 @@ type: example
 <View display="block">
   <Button size="condensedSmall" margin="small">Condensed Small</Button>
   <Button size="condensedMedium" margin="small">Condensed Medium</Button>
-  <Button size="small" margin="small">Small</Button>
 </View>
 ```
 
@@ -184,16 +195,14 @@ type: example
 
 ### Rendering Buttons without backgrounds
 
-Use backgroundless buttons for interfaces on dark backgrounds or when there is a need to deemphasize the button from another primary action on the page. Be sure to use border/text colors that meet the proper contrast ratios with whatever background they are placed on.
+Use backgroundless buttons when there is a need to deemphasize the button. Be sure to use border/text colors that meet the proper contrast ratios with whatever background they are placed on.
 
 ```js
 ---
 type: example
 ---
 <View display="block">
-  <View display="inline-block" background="primary">
-    <Button renderIcon={PlusInstUIIcon} withBackground={false} color="primary" margin="small">Click here</Button>
-  </View>
+  <Button renderIcon={PlusInstUIIcon} withBackground={false} color="secondary" margin="small">Click here</Button>
 </View>
 ```