Update proposals/2354-streaming-file-transfer.md

Co-authored-by: Jonathan de Jong <jonathandejong02@gmail.com>

proposals/2354-streaming-file-transfer.md

@@ -2,7 +2,7 @@
 
 File transfer in matrix currently works by uploading a file to the server, which is then distributed over
 the participating servers in the room, and is available through an HTTP get request to everyone who knows
-the URL. By nescesity this has a maximum filesize and also results in a more or less permanent availablity
+the URL. By necessity this has a maximum filesize and also results in a more or less permanent availability
 of said file. For larger files, and/or files that should only be sent from point-to-point, it may be desirable
 to be able to send from device to device. As matrix already implements
 [WebRTC signalling for voip](https://matrix.org/docs/spec/client_server/r0.6.0#voice-over-ip), this