Replace KSERVE-TECHNICAL-CHARTER.md with original PDF

[riaankleinhans]

As instructed by LF Project Formation team.
The project charter can not be changed without collaborating with the Formation team about the desired changes.

To complete the transfer of the project to CNCF the original charter must be added to the project repo.

[riaankleinhans]

@terrytangyuan can you please review.
Charter pulled from here:
https://github.com/lfai/foundation/blob/main/technical%20project%20charters/KServe%20Technical%20Charter%20Final.pdf

[terrytangyuan]

More context from Riaan:

LF Legal is blocking some of the transfer steps until the original charter is in the repo.
The charter is the "legal contract" that determine the rules for the project and LF Legal check changes to help project not step on landmines in the future.
The project should not delete the old charter and go back to the changed version without the approval of the Formation team.
So here is what I can propose:
Merge the PR.
Discuss with the project if the changes between the old and the new charter is what the community want.
Then I will engage with the Formation team to get the charter officially updated.