The update notes you are looking for are not usually present on the tumblr, as you noted. There are two places, however, where you can find the information you seek.
Official Mojang blog
They can, however be found in the official Mojang blog on their main site. The older posts can be hard to find though, but should be able to find them with some googling, I suggest searching for
site:mojang.com -site:bugs.mojang.com minecraft [version]
to limit the results to actual results. Note that these posts are often updated, even changing the title in some cases, such as the one for 1.8.2.
Sadly, the information about bugfixes is often scattered among multiple posts for pre-releases as well as the main post, making them hard to follow. They also seem to be incomplete.
The wiki's version history
A much more convenient way of browsing the changes is offered by the wiki, in the Version History article, neatly sorted by major and minor version. There is an extra page for development versions as well, if you want to check out the snapshots or pre-releases.
The downside is that this information is user-curated and takes some time to be gathered, especially for non-obvious changes, such as the blacklisting of player head textures not hosted on a mojang server in 1.8.4.
Best Answer
I've made an item that gives the player a jump boost when held. First, execute the following commands:
Then, put the following commands in a command block chain:
Finally, use an anvil to name a random item "Flying Orb", hold it, jump, and fly away. The code protects you from fall damage, so you won't get hurt if you fall down hard, with or without elytra equipped. The fall damage protection works even if you let go of the item in mid air.
If your computer has trouble running 8 commands each tick, you could remove the first block of code. However, doing so will allow you to jump boosted without fall damage protection if you've just let go of the item, so you have to wait one second after letting go of the item before jumping again.