Fix installation instructions

Signed-off-by: Charles de Dreuille <charles.dedreuille@gmail.com>

packages/canon/src/components/Box/Docs.mdx

@@ -17,7 +17,7 @@ import { spacingProperties } from '../../layout/sprinkles.css';
 </Text>
 
 <Title type="h2">Installation</Title>
-<Source code={`yarn install @backstage/canon/box`} language="bash" dark />
+<Source code={`import { Box } from "@backstage/canon";`} language="tsx" dark />
 
 <Title type="h2">API reference</Title>
 

packages/canon/src/components/Container/Docs.mdx

@@ -17,7 +17,11 @@ import { containerProperties } from './sprinkles.css';
 </Text>
 
 <Title type="h2">Installation</Title>
-<Source code={`yarn install @backstage/canon/container`} language="bash" dark />
+<Source
+  code={`import { Container } from "@backstage/canon";`}
+  language="tsx"
+  dark
+/>
 
 <Title type="h2" style={{ marginBottom: '16px' }}>
   API reference

packages/canon/src/components/Grid/Docs.mdx

@@ -15,7 +15,7 @@ import { spacingProperties } from '../../layout/sprinkles.css';
 </Text>
 
 <Title type="h2">Installation</Title>
-<Source code={`yarn install @backstage/canon/grid`} language="bash" dark />
+<Source code={`import { Grid } from "@backstage/canon";`} language="tsx" dark />
 
 <Title type="h2">Anatomy</Title>
 <Text>

packages/canon/src/components/Inline/Docs.mdx

@@ -18,7 +18,11 @@ import { inlineProperties } from './sprinkles.css';
 </Text>
 
 <Title type="h2">Installation</Title>
-<Source code={`yarn install @backstage/canon/inline`} language="bash" dark />
+<Source
+  code={`import { Inline } from "@backstage/canon";`}
+  language="tsx"
+  dark
+/>
 
 <Title type="h2" style={{ marginBottom: '16px' }}>
   API reference

packages/canon/src/components/Stack/Docs.mdx

@@ -17,7 +17,11 @@ import { spacingProperties } from '../../layout/sprinkles.css';
 </Text>
 
 <Title type="h2">Installation</Title>
-<Source code={`yarn install @backstage/canon/stack`} language="bash" dark />
+<Source
+  code={`import { Stack } from "@backstage/canon";`}
+  language="tsx"
+  dark
+/>
 
 <Title type="h2" style={{ marginBottom: '16px' }}>
   API reference