Remove stray <base target> (#951)

* Remove stray `<base target>`
- This was causing a new tab to be opened when clicking on the nav bar while on these pages `/projects/ssa/` and `/projects/healthcare-renewals/`
- This was may have been causing DAP issues because tracking across new tabs?
- Renamed `0008__medicaid.md` to `0008_medicaid.md` (double __ -> single _)
- Rename other files to control order
Note: We are out of space with the numbering. We'll need to renumber soon or switch to a date prefix (which avoids this issue completely).

_projects/0006_ssa.md

@@ -43,7 +43,6 @@ impact_statement:
       increase in the Customer Satisfaction Score (CSAT) since the website launch
 
 ---
-<base target="_blank">
 
 ## Overview
 

_projects/0008__medicaid.md → _projects/0008_medicaid.md

@@ -9,6 +9,10 @@ project_page: true
 carousel_title: "Cutting red tape for Americans renewing their health coverage"
 carousel_summary: "USDS worked with Center for Medicaid and CHIP Services to partner with state Medicaid agencies to help improve state eligibility and enrollment systems."
 carousel_image_name: project-medicaid-card.jpg
+# accessibility text for image
+carousel_image_alt_text: "Project photo"
+# Do not show on homepage yet
+carousel_show: false
 
 # Project detail page (Edit this)
 title: "Cutting red tape for Americans renewing their health coverage"
@@ -37,7 +41,6 @@ impact_statement:
     description: |-
       children and families reinstated for coverage across 29 states as a result of actions taken by CMCS and supported by USDS
 ---
-<base target="_blank">
 
 ## Background