Update ROADMAP.md (MystenLabs#1128)

Fix a typo
Make APIs plural rather than possessive
Convert headings to Sentence case

ROADMAP.md

@@ -1,9 +1,9 @@
 # Roadmap
 
 Currently, builders can:
-* Write and test Move smart contracts,
-* Spin up a local Sui network,
-* Publish and run Move smart contracts on a local network.
+* Write and test Move smart contracts
+* Spin up a local Sui network
+* Publish and run Move smart contracts on a local network
 
 In the coming months, we will release:
 1. A public devnet that allows Sui devs to do all of the above on a shared network powered by Mysten-operated authorities
@@ -12,33 +12,33 @@ In the coming months, we will release:
 
 A more fine-grained description of the upcoming features and improvements to the Sui codebase follows.
 
-# Ongoing Work and Upcoming Features
+## Ongoing work and upcoming features
 
-### Internal Devnet
+### Internal devnet
 * Constantly running Sui network
 * Productionizing network stack
 * Benchmarking throughput and latency in various configurations
 
-### Protocol Stabilization
+### Protocol stabilization
 
 * Implementing reconfiguration and staking
 * Ledger and state checkpoints
-* Aligning Gateway Service Rust/REST/wallet API’s
+* Aligning Gateway Service Rust/REST/wallet APIs
 * Finalizing REST data model (aka SuiJSON)
 * Finalizing core data types
-* Authority "Follower" API's to support replicas
+* Authority "Follower" APIs to support replicas
 * Integration of shared objects and consensus
 * Selecting principled gas costs
 * Event indexing hints
 
-### SDK and Ecosystem
+### SDK and ecosystem
 * Block explorer
 * Key management and wallet prototypes
 * Support package publishing via REST API
 * More informative error messages
-* More convenient API's that hide gas object selection and nested object authentication
+* More convenient APIs that hide gas object selection and nested object authentication
 
-### Move Development Improvments
+### Move development improvements
 * Allow objects used in authentication, but not passed to entrypoints
 * Explicit syntax and compiler enforcement for entrypoints
-* Adding Move Prover specs to the Sui framework and verifying in CI
+* Adding Move Prover specs to the Sui framework and verifying in continuous integration (CI)