Address Primer feedback

[jpmckinney]

closes #1370

• primer: Use "the OCDS" consistently where applicable
• primer: Remove paragraphs and bullets that repeat each other and the content on the landing page and on the last page of the primer
• primer/how: Remove image that is inconsistent due to inclusion of planning, and that is somewhat repetitive
• primer,guidance: Use "JSON text" instead of "JSON document" to avoid confusion with the documents field
• primer/releases_and_records: Use image containing both releases and records
• primer/index: Restore bullets, since the Primer also serves to outline the documentation, using same content as primer/next
• primer/what: Move significant content out of objectives. Avoid repetition of concepts. Add link to academic research. Capitalize Primer.
• primer/next,primer/releases_and_records: Add article. Capitalize Primer.
• primer/how: Align with Clarify contracts description (896) #1208 (concluding -> implementing). Add link to demand-side assessment. Clarify normative relationship between JSON and Excel/CSV. Rephrase to avoid repetition. Capitalize Primer. Copy-edit punctuation. Fix typo.