Actually you were not aware of the new site feature where a normal member can also take part in updating site information, but for that he/she has to earn 100 credits/points. I just checked yours, which is 106 right now. So, you have recently crossed 100 mark, and that's why those "edit" buttons became visible to you.
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Congratulations. Now you can contribute to the Timeline (TL) of this website directly. But remember, your entry will be waitlisted initially. Once it is verified by a Timeline Monitor and he approves it, then...
more... only it will be shown in the webpage. Therefore, whenever you are making some editions/changes, please keep in mind that your entry will only be shown after the approval. So please don't make multiple entries. We reject the other entries as duplicate ones. Thanks.