Update Flutter wallet SDK install snippet to current release, drop stale general SDK pin - #2810

Update Flutter wallet SDK install snippet to current release, drop stale general SDK pin#2810

kaankacar with Copilot wants to merge 2 commits into

mainstellar/stellar-docs:mainfrom

copilot/avoid-stale-sdk-version-pinsstellar/stellar-docs:copilot/avoid-stale-sdk-version-pinsCopy head branch name to clipboard