Update Documentation: Standardize English to American Spelling

[futreall]

Description

This pull request replaces British English spellings with American English spellings (e.g., "behaviour" to "behavior") across the documentation to ensure consistency and alignment with the project's predominantly American English usage.

Why This Change Is Important:
Consistency: The project predominantly uses American English throughout its documentation. Replacing British spellings like "behaviour" with "behavior" ensures consistency and aligns with the overall writing style.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have selected the correct base branch.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• Any dependent changes have been merged and published in downstream modules.
• I ran npm run lint with success and extended the tests and types if necessary.
• I ran npm run test:unit with success.
• I ran npm run test:coverage and my test cases cover all the lines and branches of the added code.
• I ran npm run build and tested dist/web3.min.js in a browser.
• I have tested my code on the live network.
• I have checked the Deploy Preview and it looks correct.
• I have updated the CHANGELOG.md file in the root folder.
• I have linked Issue(s) with this PR in "Linked Issues" menu.

[danforbes]

Thank you for spotting these errors @futreall. In order to protect against airdrop farming, we have a policy against merging pull requests that only include typo changes. We will fold your corrections into other documentation PRs. Please feel free to refer to the Issues labeled "Good First Issue" if you're looking for ways to contribute to Web3.js.