docs/comments: fix doubled-word typos

Pure typo fixes in user-facing manpages, interface changelog, and
source comments. No behavior change.

- DOCS/man/encode.rst: "copying of the the comment" -> "copying of the comment"
- DOCS/man/options.rst: "visible takes the the menu bar" -> "takes the menu bar"
- DOCS/interface-changes.rst: "rename the the lua-settings/" -> "rename the lua-settings/"
- video/out/present_sync.c: "requires that that caller" -> "requires that the caller"
- player/lua.c: "try to get by by filtering" -> "try to get by filtering"