fix: broken blockchain urls (#177)

## Summary by Sourcery

Bug Fixes:
- Fixes broken links to blockchain guides by correcting the casing of
the URLs.

Author: insider89

content/docs/about-settlemint/supported-blockchains.mdx

@@ -54,7 +54,7 @@ SettleMint currently supports the following protocols:
 
 <Cards>
   <Card
-    href="/blockchain-guides/ethereum/1_ethereum-the-basics"
+    href="/blockchain-guides/Ethereum/1_ethereum-the-basics"
   >
     <h3 className="mb-4">Ethereum</h3>
     <div className="flex flex-col items-center gap-8">
@@ -66,7 +66,7 @@ SettleMint currently supports the following protocols:
   </Card>
 
   <Card
-    href="/blockchain-guides/avalanche/1_avalanche-the-basics"
+    href="/blockchain-guides/Avalanche/1_avalanche-the-basics"
   >
     <h3 className="mb-4">Avalanche</h3>
     <div className="flex flex-col items-center gap-4">
@@ -78,7 +78,7 @@ SettleMint currently supports the following protocols:
   </Card>
 
   <Card
-    href="/blockchain-guides/polygon/1_polygon-the-basics"
+    href="/blockchain-guides/Polygon/1_polygon-the-basics"
   >
     <h3 className="mb-4">Polygon</h3>
     <div className="flex flex-col items-center gap-4">
@@ -90,7 +90,7 @@ SettleMint currently supports the following protocols:
   </Card>
 
   <Card
-    href="/blockchain-guides/polygon-zkevm/1_polygon-zkevm-the-basics"
+    href="/blockchain-guides/Polygon-zkEVM/1_polygon-zkevm-the-basics"
   >
     <h3 className="mb-4">Polygon zkEVM</h3>
     <div className="flex flex-col items-center gap-4">