docs: Clarify inject data when multiple parent provide the same key

[kfina-planxy]

Description of Problem

It was unclear in the docs, how the situation is handled if multiple parents provide the same key.

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[AloisSeckar]

I am just translating this into cs.vuejs.org and this sentence doesn't clarified it much for me. Is it the "first" going up from the root component or closest to the injecting child?

My second objection: This only added the sentence into Options API block and not the Composition API one...

I will think about an improvment and post the PR soon

[kfina-planxy]

Closest to the child:
Starting from the child that injects you go to its parent and check if its parent provides that key. If so, use that key, otherwise go to the its parent and check again.

Example:

    [ A ] provides: x=1
   /     \
[ C ]   [ B ] provides: x=2
x=1        \
           [ C ]
            x=2