chore: fixed 2 markdown syntax or links (#12811)

fix links

Author: wgyt

documentation/changelog/CHANGELOG_1.2x.md

@@ -2012,9 +2012,9 @@ The `lotus-miner sector list` is now running in parallel - which should speed up
 
 - backport: fix: miner: correctly count sector extensions (10555) ([filecoin-project/lotus#10555](https://github.com/filecoin-project/lotus/pull/10555))
    - Fixes the issue with sector extensions.
-- fix: proving: Initialize slice with with same length as partition (#10574) ([filecoin-project/lotus#10574])(https://github.com/filecoin-project/lotus/pull/10574)
+- fix: proving: Initialize slice with with same length as partition (#10574) ([filecoin-project/lotus#10574](https://github.com/filecoin-project/lotus/pull/10574))
    - Fixes an issue where `lotus-miner proving compute window-post` paniced when trying to make skipped sectors human readable.
-- feat: stmgr: speed up calculation of genesis circ supply (#10553) ([filecoin-project/lotus#10553])(https://github.com/filecoin-project/lotus/pull/10553)
+- feat: stmgr: speed up calculation of genesis circ supply (#10553) ([filecoin-project/lotus#10553](https://github.com/filecoin-project/lotus/pull/10553))
 - perf: eth: gas estimate set applyTsMessages false (#10546) ([filecoin-project/lotus#10456](https://github.com/filecoin-project/lotus/pull/10546))
 - feat: config: Force existing users to opt into new defaults (#10488) ([filecoin-project/lotus#10488](https://github.com/filecoin-project/lotus/pull/10488))
    - Force existing users to opt into the new SplitStore defaults.