Edit for readability, added Border-Image section (#20814)
Edit for readability, added Border-Image section (#20814)

Made a few punctuation edits and rephrased sentences.
Added border-image section.
Removed other properties section because border-image is now its own section and border-spacing is a table property and not related to other border properties.
jonathanihm/freeCodeCamp,BhaveshSGupta/FreeCodeCamp,FreeCodeCamp/FreeCodeCamp,BhaveshSGupta/FreeCodeCamp,BhaveshSGupta/FreeCodeCamp,raisedadead/FreeCodeCamp,raisedadead/FreeCodeCamp,jonathanihm/freeCodeCamp,FreeCodeCamp/FreeCodeCamp