update CDK intros done

Author: EmpieichO

docs/cdk/concepts/dac.md

@@ -24,7 +24,7 @@ The CDK validium DAC is a secure consortium of nodes that ensures off-chain data
 
 ## DAC data flow
 
-![CDK validium DAC dataflow](../../img/cdk/zksupernets-dac.png)
+![CDK validium DAC dataflow](../../img/cdk/cdk-val-dac-02.png)
 
 The DAC works together with the sequencer to control the flow of data. The process can be broken down as follows:
 

docs/cdk/concepts/index.md

@@ -1 +1,3 @@
-Welcome to the Concepts section.
+This section covers some of the basic concepts needed to understand the CDK setting, which is a platform designed to allow developers to choose between validium and zk-rollup architectures.
+
+Concepts such as a rollup, a validium and data availability committee (DAC) are defined. Implications of off-chain data availability are briefly discussed.

docs/cdk/concepts/validium.md

@@ -1,4 +1,4 @@
-Validiums are blockchain scaling solutions that do not store transaction data.
+Validiums are blockchain scaling solutions that do not store transaction data on-chain.
 
 !!! info "Recommended resource"
     See Ethereum.org's detailed [description of validiums](https://ethereum.org/en/developers/docs/scaling/validium/).

docs/cdk/how-to/index.md

@@ -1 +1,4 @@
-This introduction to the how to section is being written.
+This section describes how to manage policies pertaining to data access in the case of a Validium.
+
+Validia store data off-chain, and with this option comes the need to manage both the data and access to the data. This is facilitated through policies that stipulate which addresses can have access to data. Lists of addresses, such as the Allowlist and Denylist, are therefore kept to exclude or include certain addresses to having access.
+

docs/cdk/spec/index.md

@@ -1 +1,7 @@
-This introduction to the specification section is being written.
+This section gives a comparison between a validium and a zk-rollup. 
+
+The main difference is the fact that a validium has a data availability layer whereas a zk-rollup does not. This difference alone is the reason for the substantially reduced gas fees for a validium compared to the zk-rollup.
+
+However, with this off-chain data availability, there is a trade-off between gas fees and security. Unlike in the zk-rollup, where forced batches are activated, the validium suffers from the possibility for the sequencer to go offline or the DAC to collude among themselves to withold state data.
+
+What remains common between the two architectures is the generation of proofs.