Fixes #1715
If the cog is reloaded while there are less than the maximum amount of available channels, it makes some channels available until the limit is reached. When a channel is made available, it updates the available_help_channels set. The update_available_help_channels() function would not update this set if it sees that the set already contains elements. This resulted in only the channels that were just made available being in the set; the set would not contain the channels tha...




