Made changes to the Transaction weight definition

[OLUWAMUYIWA]

• Are the audience and objective of the document clear? E.g. a document for developers that should teach them about transaction fees.
• Is the writing:
  • Clear: No jargon.
  • Precise: No ambiguous meanings.
  • Concise: Free of superfluous detail.
• Does it follow our style guide?
• If this is a new page, does the PR include the appropriate infrastructure, e.g. adding the page to a sidebar?
• Build the page ($ cd website && yarn start). Does it render properly? E.g. no funny lists or formatting.
• Do links go to rustdocs or devhub articles rather than code?
• If this PR addresses an issue in the queue, have you referenced it in the description?

[nuke-web3]

Thanks!!