message: Remove outdated dangling underscore
diff: @@ -23,6 +23,6 @@ As of https://github.com/matrix-org/matrix-react-sdk/pull/4166, we are scrolling
  ### How does it work?
  -`componentDidUpdate` is called when a tile in the timeline is updated (as we rerender the whole timeline) or tiles are added or removed (see Updates section before). From here, `checkScroll` is called, which calls `_restoreSavedScrollState`. Now, we increase the timeline height if something below the viewport grew by adjusting `this._bottomGrowth`. `bottomGrowth` is the height added to the timeline (on top of the height from the number of pages calculated at the last `_updateHeight` run) to compensate for growth below the viewport. This is cleared during the next run of `_updateHeight`. Remember that the tiles in the timeline are aligned to the bottom.
  +`componentDidUpdate` is called when a tile in the timeline is updated (as we rerender the whole timeline) or tiles are added or removed (see Updates section before). From here, `checkScroll` is called, which calls `restoreSavedScrollState`. Now, we increase the timeline height if something below the viewport grew by adjusting `this.bottomGrowth`. `bottomGrowth` is the height added to the timeline (on top of the height from the number of pages calculated at the last `updateHeight` run) to compensate for growth below the viewport. This is cleared during the next run of `updateHeight`. Remember that the tiles in the timeline are aligned to the bottom.
  -From `_restoreSavedScrollState` we also call `_updateHeight` which waits until the user stops scrolling for 100ms and then recalculates the amount of pages of 400px the timeline should be sized to, to be able to show all of its (newly added) content. We have to adjust the scroll offset (which is why we wait until scrolling has stopped) now because the space above the viewport has likely changed.
  +From `restoreSavedScrollState` we also call `updateHeight` which waits until the user stops scrolling for 100ms and then recalculates the amount of pages of 400px the timeline should be sized to, to be able to show all of its (newly added) content. We have to adjust the scroll offset (which is why we wait until scrolling has stopped) now because the space above the viewport has likely changed.
  