Fix misspellings
Note: In optimization-guide/C/harmful.page, I'm unsure whether "mmaped" should be "mapped" or "mmapped" (as in mmap syscall). I chose the latter.
Note: In optimization-guide/C/harmful.page, I'm unsure whether "mmaped" should be "mapped" or "mmapped" (as in mmap syscall). I chose the latter.