Fixed a lot of grammatical errors in CONTRIBUTING.md

[Shaheer-Ahmd]

Brief Information

Fixed grammatical errors in CONTRIBUTING.md and README.md
This pull request is in the type of:

• bug fixing
• new feature
• others <--

What does this PR do?

Fixed a lot of grammatical errors in CONTRIBUTING.md and README.md

Fixed issues

Fixed a lot of grammatical errors in CONTRIBUTING.md and README.md

Details

Fixed a lot of grammatical errors in CONTRIBUTING.md and README.md

Before: What was the problem?

Many sentences had grammatical errors.

After: How does it behave after the fixing?

Fixed a lot of grammatical errors in CONTRIBUTING.md

Document Info

One of the following should be checked.

• This PR doesn't relate to document changes <--
• The document should be updated later
• The document changes have been made in apache/echarts-doc#xxx

Misc

ZRender Changes

• This PR depends on ZRender changes (ecomfe/zrender#xxx).

Related test cases or examples to use the new APIs

N.A.

Others

Merging options

• Please squash the commits into a single one when merging.

Other information

[echarts-bot]

Thanks for your contribution!
The community will review it ASAP. In the meanwhile, please checkout the coding standard and Wiki about How to make a pull request.

⚠️ MISSING DOCUMENT INFO: Please make sure one of the document options are checked in this PR's description. Search "Document Info" in the description of this PR. This should be done either by the author or the reviewers of the PR.

[Shaheer-Ahmd]

@plainheart can you review this?

[echarts-bot]

Congratulations! Your PR has been merged. Thanks for your contribution! 👍