feat: add a template (archetype) for adding new authors

I thought this would be useful for people who need to create many authors. Instead of copying and pasting the `admin/_index.md`, they can simply use the hugo command `hugo new authors/FIRSTNAME-LASTNAME` and have an empty but commented _index.md file ready to be filled in for each author.

Close #1445

archetypes/authors/_index.md

@@ -0,0 +1,68 @@
+---
+# Display name
+name: "{{ replace .Name "-" " " | title }}"
+
+# Username (this should match the folder name and the name on publications)
+authors:
+- Name "{{ replace .Name "-" " " | title }}"
+
+# Is this the primary user of the site?
+superuser: false
+
+# Role/position (e.g., Professor of Artificial Intelligence)
+role:
+
+# Organizations/Affiliations
+organizations:
+- name: 
+  url: ""
+
+# Short bio (displayed in user profile at end of posts)
+bio: 
+
+# List each interest with a dash
+interests:
+- Interest 1
+- Interest 2
+
+education:
+  courses:
+  - course: Title course 1
+    institution: Name of Institution
+    year: 2012
+  - course: Title course 1
+    institution: Name of Institution
+    year: 2012
+
+# Social/Academic Networking
+# For available icons, see: https://sourcethemes.com/academic/docs/page-builder/#icons
+#   For an email link, use "fas" icon pack, "envelope" icon, and a link in the
+#   form "mailto:your-email@example.com" or "#contact" for contact widget.
+social:
+- icon: envelope
+  icon_pack: fas
+  link: '#contact'  # For a direct email link, use "mailto:test@example.org".
+- icon: twitter
+  icon_pack: fab
+  link: https://twitter.com/USERNAME
+- icon: google-scholar
+  icon_pack: ai
+  link: https://scholar.google.com/citations?user=PERSON-ID
+- icon: github
+  icon_pack: fab
+  link: https://github.com/USERNAME
+# Link to a PDF of your resume/CV from the About widget.
+# To enable, copy your resume/CV to `static/files/cv.pdf` and uncomment the lines below.
+# - icon: cv
+#   icon_pack: ai
+#   link: files/cv.pdf
+
+# Enter email to display Gravatar (if Gravatar enabled in Config)
+email: ""
+
+# Organizational groups that you belong to (for People widget)
+#   Set this to `[]` or comment out if you are not using People widget.
+user_groups:
+- Group 1
+- Group 2
+---