chore: Add some minor fixes

Author: zguesmi

src/index.md

@@ -234,7 +234,7 @@ features:
       23.625H11.5835C12.2038 23.625 12.7085 24.1297 12.7085
       24.75V27.0538C12.7084 27.0595 12.7085 27.0652 12.7085
       27.0709V29.25C12.7085 29.8703 12.2038 30.375 11.5835 30.375Z" /> </svg>
-    title: Protocols
+    title: Protocol
     details:
       Deep dive into core protocol concepts. Understand how iExec enables
       privacy, governance, and monetization.

src/protocol/proof-of-contribution.md

@@ -461,7 +461,7 @@ struct AppOrder
 - `sign` cryptographic signature of the order, the smart contract is securely
   linked to application owner.
 
-### **DatasetOrder**
+#### **DatasetOrder**
 
 ```text
 struct DatasetOrder
@@ -494,7 +494,7 @@ struct DatasetOrder
 - `sign` cryptographic signature of the order, the smart contract is securely
   linked to dataset owner.
 
-### **WorkerpoolOrder**
+#### **WorkerpoolOrder**
 
 ```text
 struct WorkerpoolOrder
@@ -531,7 +531,7 @@ struct WorkerpoolOrder
 - `sign` cryptographic signature of the order, the smart contract is securely
   linked to worker pool manager.
 
-### **RequesterOrder**
+#### **RequesterOrder**
 
 ```text
 struct RequestOrder