Docs/core-api: fix typos in rbtree.rst

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Computing the leftmost (smallest) node is quite a common task for binary

search trees, such as for traversals or users relying on a the particular

search trees, such as for traversals or users relying on the particular

order for their own logic. To this end, users can use 'struct rb_root_cached'

to optimize O(logN) rb_first() calls to a simple pointer fetch avoiding

potentially expensive tree iterations. This is done at negligible runtime

When erasing a node, the user must call rb_erase_augmented() instead of

rb_erase(). rb_erase_augmented() calls back into user provided functions

to updated the augmented information on affected subtrees.

to update the augmented information on affected subtrees.

In both cases, the callbacks are provided through struct rb_augment_callbacks.

3 callbacks must be defined:

This "extra information" stored in each node is the maximum hi

(max_hi) value among all the nodes that are its descendants. This

information can be maintained at each node just be looking at the node

information can be maintained at each node just by looking at the node

and its immediate children. And this will be used in O(log n) lookup

for lowest match (lowest start address among all possible matches)

with something like::