Correct spelling mistakes.

code/qcommon/files.c

@@ -88,7 +88,7 @@ File search order: when FS_FOpenFileRead gets called it will go through the fs_s
 structure and stop on the first successful hit. fs_searchpaths is built with successive
 calls to FS_AddGameDirectory
 
-Additionaly, we search in several subdirectories:
+Additionally, we search in several subdirectories:
 current game is the current mode
 base game is a variable to allow mods based on other mods
 (such as baseq3 + missionpack content combination in a mod for instance)
@@ -1420,7 +1420,7 @@ long FS_FOpenFileRead(const char *filename, fileHandle_t *file, qboolean uniqueF
 	}
 	else
 	{
-		// When file is NULL, we're querying the existance of the file
+		// When file is NULL, we're querying the existence of the file
 		// If we've got here, it doesn't exist
 		return 0;
 	}
@@ -3931,7 +3931,7 @@ void FS_PureServerSetReferencedPaks( const char *pakSums, const char *pakNames )
 ================
 FS_InitFilesystem
 
-Called only at inital startup, not when the filesystem
+Called only at initial startup, not when the filesystem
 is resetting due to a game change
 ================
 */