fix: doc model_composition.md Basic Deployment line number Example

[klebster2]

Update line numbers (some of the line numbers were inaccurate).

Why are these changes needed?

Fixing an inaccurate line number references in an example found in the docs (specifically, the serve documentation).

This is to increase readability for those interested in the docs. Here is the problematic doc: Basic Deployment Example.

Related issue number

None known

Checks

• I've signed off every commit(by using the -s flag, i.e., git commit -s) in this PR.
• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
  • I've added any new APIs to the API Reference. For example, if I added a
    method in Tune, I've added it in doc/source/tune/api/ under the
    corresponding .rst file.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(

[edoakes]

Thanks!