Main README.md: Fix run-on line after URL at "BUILDING on MacOS"
Main README.md: Fix run-on line after URL at "BUILDING on MacOS"

opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,ampli/link-grammar,opencog/link-grammar,opencog/link-grammar,linas/link-grammar,opencog/link-grammar,opencog/link-grammar,linas/link-grammar,ampli/link-grammar,opencog/link-grammar,linas/link-grammar,ampli/link-grammar,opencog/link-grammar,linas/link-grammar,linas/link-grammar,ampli/link-grammar,linas/link-grammar,linas/link-grammar,ampli/link-grammar,ampli/link-grammar,linas/link-grammar