Corrects spelling error in README.md
Corrects spelling error in README.md

optomized -> optimized
rlivsey/intl-messageformat,yahoo/intl-messageformat,mattikl/intl-messageformat,ericf/intl-messageformat,rlivsey/intl-messageformat,yahoo/intl-messageformat,jeffvan576/intl-messageformat,jeffvan576/intl-messageformat,ericf/intl-messageformat,ericf/intl-messageformat,jeffvan576/intl-messageformat,rlivsey/intl-messageformat,mattikl/intl-messageformat,mattikl/intl-messageformat,yahoo/intl-messageformat