chore: correction typos index.md

[osrm]

correction grammar errors

The standard library has it's own reference documentation that has detailed information about each module in std. => The standard library has its own reference documentation that has detailed information about each module in std.

"it's" should be corrected to "its". "It's" is a contraction for "it is", while "its" is the possessive form.

Similar to ERC standards for Ethereum and Solidity, Sway has it's own SRC standards... => Similar to ERC standards for Ethereum and Solidity, Sway has its own SRC standards...

"it's" should be corrected to "its".

Description

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.

[CLAassistant]

All committers have signed the CLA.