Fixing the docstring of Batch

[SamFerracin]

Summary

The docstring of batch is incorrect. Additonaly, the example shown is trivial, as it shows how to open a batch mode to run a single circuit. This PR fixes both issues.

Details and comments

Fixes # 1696

[coveralls]

Pull Request Test Coverage Report for Build 9586226089

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 82.0%

---

Totals
Change from base Build 9584804898:	0.0%
Covered Lines:	6077
Relevant Lines:	7411

---

💛 - Coveralls

[jyu00]

Some minor comments but otherwise LGTM!

[coveralls]

Pull Request Test Coverage Report for Build 9604841596

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 82.0%

---

Totals
Change from base Build 9584804898:	0.0%
Covered Lines:	6077
Relevant Lines:	7411

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 9604987773

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 82.0%

---

Totals
Change from base Build 9601825612:	0.0%
Covered Lines:	6077
Relevant Lines:	7411

---

💛 - Coveralls