Finnish translation for “Getting Started” file (Brackets 1.0)

Also changed max line length to 120 character which is same as it in the English (root) “Getting Started” file.
Update index.html
Update index.html
Update index.html
Change ”→” back to ”&gt;”
Fix line length
Changes based on PR #9691
Merge pull request #9683 from valtlait/patch-4

Update Finnish translation for “Getting Started” file (Brackets 1.0)