Fix typo in documentation

[Alan-Cha]

No description provided.

[leecalcote]

Thanks for jumping in here, @Alan-Cha. This statement is slightly deceiving in that "weigh" as a verb makes intuitive sense, although, "weight" being used as a verb is actually appropriate.

The intended meaning here, is that implementations will allocate a certain amount of "weight" to traffic to determine their appropriate destination. I think this becomes much more clear when the word "assign" is added, like so: "Implementations will assign weight to outgoing traffic between the services referenced by..."

In lieu of this understanding, I'll suggest that we either close this PR or toss in the word "assign" for clarification.

[michelleN]

@Alan-Cha Would you like to update the PR based on Lee's suggestion?

#222 (review)

[bridgetkromhout]

Closing due to project archival: https://www.cncf.io/blog/2023/10/03/cncf-archives-the-service-mesh-interface-smi-project/)