chore: add @joshuali925 as maintainer and code owner

[ps48]

Description

Add @joshuali925 as maintainer and code owner for the observability-stack repository.

Contributions to observability-stack:

• fix(docs): resolve npm audit vulnerabilities (fix(docs): resolve npm audit vulnerabilities #177) (abc5487)
• docs: use npx for cli instructions (docs: use npx for cli instructions #184) (7d355f4)
• rename release CI to release-drafter (rename release CI to release-drafter #182) (067610c)
• bump cli to v0.1.1 (bump cli to v0.1.1 and fix npm #176) (12f69bc)
• feat(cli): add release drafter for 0.1.0 (feat(cli): add release drafter for 0.1.0 #173) (d46639c)
• feat(cli): increase fish pipe length and add demo video (feat(cli): increase fish pipe length and add demo video #170) (75af4dd)
• update CLI get started command to use one line script (update CLI get started command to use one line script #162) (f801b8a)
• feat(cli): use domain and pipeline status text for animation (feat(cli): use domain and pipeline status text for animation #157) (bbb986a)
• feat(cli): improve ASCII animations (feat(cli): improve ASCII animations #155) (2398f80)
• [cli] Fix bugs and improve UI (#154)