docs: update Tera documentation link to the correct Introduction section

[VolodymyrBg]

Replaced the outdated Tera documentation URL in cliff.toml with the current and correct link pointing directly to the Introduction section: https://keats.github.io/tera/docs/#introduction
This ensures users are directed to the relevant part of the documentation.

[codspeed-hq]

CodSpeed Performance Report

Merging #107 will improve performances by 13.9%

_{Comparing VolodymyrBg:fix-broken-link (6c56976) with main (816689b)}

Summary

⚡ 4 improvements

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	trie[16]	418.1 ns	359.7 ns	+16.22%
⚡	trie[32]	438.1 ns	379.7 ns	+15.36%
⚡	trie[64]	478.1 ns	419.7 ns	+13.9%
⚡	trie[8]	408.1 ns	349.7 ns	+16.68%