add explicit copyright header to docs CSS & JS files. even shorter banner; remove space between slash and period

BS3 commits: c88cd1cd95dc4bef63697124f795fe7e60308a99,
1f33dc8033b2b8245df98a79ebe8800c6c0b992e
copy change, add to buttons anchor section. Resolves 10923

BS3 commits: 96a19c18fbef89a4f4ae261ae78e7fc26e9d2dd8,
4c043b7d5f3f9d1f7c4ebe1e82c77b29d282fc39
copy change for the masthead and toolbar