message: Fixed grammar and changed wording in README.md
diff: ## Nebula
  -**Nebula** is the only solution in the world capable to host graphs with dozens of billions of vertices (nodes) and trillions of edges, while still provides millisecond latency.
  +**Nebula** is the only solution in the world capable of hosting graphs with dozens of billions of vertices (nodes) and trillions of edges, while still only having milliseconds of latency.
  -**Nebula's** goal is to provide reading, writing, and computing with high concurrency, low latency for super large scale graphs. Nebula is an open source project and we are looking forward to working with the community to popularize and promote the graph database.
  +**Nebula's** goal is to provide reading, writing, and computing with high concurrency and low latency for super large scale graphs. Nebula is an open source project and we are looking forward to working with the community to popularize and promote the graph database.
  As a graph database, **Nebula** has these features
  * Symmetrically distributed
  @@ -29,15 +29,15 @@ Apart from installing **Nebula Graph** from source code, you can use the [offici
  ## How can I contribute ##
  As the team behind **Nebula**, we fully commit to the community and all-in to the open source project. All the core features are and will be implemented in the open source repository.
  -We also encourage the community to involve the project. There are a few ways you can contribute:
  +We also encourage the community to be involved in the project. There are a few ways you can contribute:
  * You can download and try **Nebula**, and provide us feedbacks
  * You can submit your feature requirements and bug reports
  -* You can perfectionate documentations
  +* You can improve documentation
  * You can fix bugs or implement features. More details on how to build the project and submit the Pull Requests click [`how-to-contribute`](https://github.com/vesoft-inc/nebula/blob/master/docs/how-to-contribute.md).
  ## Licensing ###
  -**Nebula** is under [Apache 2.0](https://www.apache.org/licenses/LICENSE-2.0) license, so you can freely download, modify, deploy the source code to meet your needs. You can also freely deploy **Nebula** as a back-end service to support your SaaS deployment.
  +**Nebula** is under [Apache 2.0](https://www.apache.org/licenses/LICENSE-2.0) license, so you can freely download, modify, and deploy the source code to meet your needs. You can also freely deploy **Nebula** as a back-end service to support your SaaS deployment.
  In order to prevent cloud providers monetizing from the project without contributing back, we added [Commons Clause 1.0](https://commonsclause.com/) to the project. As mentioned above, we fully commit to the open source community. We would love to hear your thoughts on the licensing model and are willing to make it more suitable for the community.
  