docs: fix typos and improve accuracy in README.md and contributing guide#281

cluster2600 wants to merge 1 commit intoNVIDIA:masterNVIDIA/DCGM:masterfrom

cluster2600:docs/fix-readme-typos-and-improve-build-guidecluster2600/DCGM:docs/fix-readme-typos-and-improve-build-guideCopy head branch name to clipboard