Expand & enhance codemeta.json

This changes `maintainer` to be a person object, and adds fields
`readme`, `programmingLanguage`, and `dateCreated`.

Author: mhucka

codemeta-TEMPLATE.json

@@ -1,10 +1,11 @@
 {
   "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
   "@type": "SoftwareSourceCode",
-  "description": "%DESCRIPTION%",
   "name": "%REPO_NAME%",
+  "description": "%DESCRIPTION%",
   "codeRepository": "https://github.com/caltechlibrary/%REPO_NAME%",
   "issueTracker": "https://github.com/caltechlibrary/%REPO_NAME%/issues",
+  "readme": "https://github.com/caltechlibrary/%REPO_NAME%/blob/main/README.md",
   "license": "https://github.com/caltechlibrary/%REPO_NAME%/blob/main/LICENSE",
   "version": "0.0.0",
   "author": [
@@ -16,13 +17,22 @@
       "email": "%AUTHOR_EMAIL%",
       "@id": "https://orcid.org/YOUR-ORCID"
     }],
+  "dateCreated": "%CREATION_DATE%",
+  "programmingLanguage": {
+    "@type": "ComputerLanguage",
+    "name": "Python",
+    "url": "https://python.org"
+  },
   "developmentStatus": "active",
   "downloadUrl": "https://github.com/caltechlibrary/%REPO_NAME%/archive/main.zip",
   "keywords": [
     "software",
     "science"
   ],
-  "maintainer": "https://orcid.org/YOUR-ORCID",
+  "maintainer": {
+    "@type": "Person",
+    "@id": "https://orcid.org/YOUR-ORCID"
+  },
   "funder": { 
           "@id": "https://doi.org/10.13039/100006961",
           "@type": "Organization",