README: add section with clearer compatibility and development steps (c…

…osmos#1011)

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## Overview

Added a section to the README to make it more explicit as to which
versions rollkit is compatible with with celestia and how to use the
local devnet vs arabica and mocha.
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- [x] New and updated code has appropriate documentation
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Makefile

@@ -33,6 +33,12 @@ lint:
 
 .PHONY: lint
 
+## fmt: Run fixes for linters. Currently only markdownlint.
+fmt:
+	@echo "--> Formatting markdownlint"
+	@markdownlint --config .markdownlint.yaml '**/*.md' -f
+.PHONY: fmt
+
 ## test-unit: Running unit tests
 test-unit:
 	@echo "--> Running unit tests"

README.md

@@ -20,6 +20,44 @@ cd rollkit
 go build -v ./...
 ```
 
+## Building With Rollkit
+
+While Rollkit is a modular framework that aims to be compatible with a wide
+range of data availability layers, settlement layers, and execution
+environments, the most supported development environment is building on Celestia
+as a data availability layer.
+
+### Building On Celestia
+
+There are currently 2 ways to build on Celestia:
+
+1. Using a local development environment with [local-celestia-devnet](https://github.com/rollkit/local-celestia-devnet)
+1. Using the Arabica or Mocha Celestia testnet
+
+#### Local Development Environment
+
+The current Rollkit v0.8.1 release is compatible with the
+[local-celestia-devnet](https://github.com/rollkit/local-celestia-devnet)
+v0.10.4 release. This version combination is compatible with
+[celesita-app](https://github.com/celestiaorg/celestia-app) v0.13.3 and
+[celestia-node](https://github.com/celestiaorg/celestia-node) v0.10.4.
+
+For more information see the [release
+notes](https://github.com/rollkit/local-celestia-devnet/releases/tag/v0.10.4)
+for v0.10.4 of local-celestia-devnet.
+
+#### Arabica and Mocha Testnets
+
+> :warning: **Rollkit v0.8.1 is not compatible with latest releases of Arabica and Mocha.** :warning:
+
+Arabica compatibility is currently under development on the `arabica` branch of
+the rollkit repo. If you are need to test or build on Arabica, please reach out
+the Rollkit team and track the progress of the `arabica` branch and the
+v0.8.2-rcx releases.
+
+The key updates to making Rollkit compatible with Arabica and Mocha are making
+Rollkit compatible with celestia-app v1.0.0-rcX and celestia-node v0.11.0-rcX.
+
 ### Tools
 
 1. Install [golangci-lint](https://golangci-lint.run/usage/install/)