[DOC OCP] Fix various formatting issues

Fix the following issues that were noted during quality checking the AMQ Streams on OCP documentation on March 18, 2019:

• 2.2.1: Uneven spacing around the architecture diagram.
• 2.2.2: Single-step procedure should use a bullet, not a number.
• 2.7.1: Uneven spacing around the Topic Operator diagram. NOT DONE
• 3.1.4.4: Visible markup in the procedure; step numbers are broken.
• 3.1.17.3.4: Punctuation missing from steps.
• 3.1.18: Visible markup in the procedure.
• 3.1.19: Visible markup in the procedure.
• 3.1.21 AND 3.1.22: Visible markup in the procedures; step numbers are broken.
• 3.2.12.3.3: Typo - "tolerations ca be configured".
• 3.3.8: Poorly worded first sentence on healthchecks and punctuation missing.
• 4.1.1: Uneven spacing around the Cluster Operator diagram. NOT DONE
• 5.4. Deleting a topic: Single-step procedure should use a bullet.
• 6.6: Visible markup in the procedure.
• 6.7: Single-step procedure should use a bullet.
• 7.5.3: Code block formatting applied to a regular paragraph.