fix: update file paths missed in 2.0

[odadacharles]

• Have you updated CHANGELOG.md with relevant non-documentation file changes?
• Have you updated the documentation for this change?

---

According to the sphinx-llm docs, the second = in SPHINX_AUTOBUILD_OPTS ?= -D=llms_txt_enabled=0 is supposed to be a space.
Ref: https://pypi.org/project/sphinx-llm/

[odadacharles]

This doesn't seem to affect the running of the make run command, so it may not be a necessary change.

[jahn-junior]

Thanks, Charles!