Language/description updates for stock missions

Hey azadam thanks for the changes, but MissionController no longer uses the single missions anymore.. These are just left over code that Nobody has never got rid of.. You now have to edit the Mission Packages (.mpkg) to have any effect on the current missions.. And they were not included in the GetHub Repo.. I will remedy this situation and make sure to add them all to the Gethub as soon as possible.. I will accept the pull request for you can see this.. But the changes will have no effect on current mission structure. :(

Hey there, I just flew through the first few of the stock missions and ended up having to repeat a few of them since the descriptions weren't entirely clear.  I went through the mission files and updated them with new descriptions based on the mission specs in the files, just wanted to offer you the update in case it might help others!

I also added a requirements for antennae to the Mun I mission since it kind of made the mission a little easier to explain and didn't really change the difficulty.