Add README.md and fix META packaging metadata (fixes #35)

Adds a README documenting installation, roles, key concepts, and the
full public API, carried forward from PR #2 and verified against the
current schema (object__describe/identity/cleanup, capture__*, object
group functions).

Fixes META.in.json (source for the generated META.json): adds cat_tools
to runtime.requires (a real, current dependency per object_reference.control),
updates decibel/* org URLs to Postgres-Extensions/*, and bumps the stated
PostgreSQL build requirement from 9.5.0 to 12.0.0, matching the floor
already established by this repo's CI matrix (derived from cat_tools's
own 12.0.0 build requirement).

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jnasbyupgrade

META.in.json

@@ -9,7 +9,7 @@
     "X_comment": "The pgxntool Makefile will strip out empty keys to produce a working META.json, so it's fine to leave them here.",
     "X_comment": "NOTE: Don't get too cute with reformatting this file... some of the processing against it doesn't use a full JSON parser",
     "X_comment": "",
-    "X_comment": "I've tried to put things in a logical order. Comments welcome at https://github.com/decibel/pgxntool/issues!",
+    "X_comment": "I've tried to put things in a logical order. Comments welcome at https://github.com/Postgres-Extensions/pgxntool/issues!",
 
     "X_comment": "REQUIRED. Name of distribution.",
     "X_comment": "Note! Distribution names currently can't contain spaces.",
@@ -58,13 +58,13 @@
 
     "X_comment": "Optional. \"resources\": Web resources available for this distribution. http://pgxn.org/spec/#resources",
     "resources": {
-        "homepage": "http://github.com/decibel/object_reference/",
+        "homepage": "http://github.com/Postgres-Extensions/object_reference/",
         "bugtracker": {
-            "web": "http://github.com/decibel/object_reference/issues"
+            "web": "http://github.com/Postgres-Extensions/object_reference/issues"
         },
         "repository": {
-            "url": "git://github.com/decibel/object_reference.git",
-            "web": "http://github.com/decibel/object_reference/",
+            "url": "git://github.com/Postgres-Extensions/object_reference.git",
+            "web": "http://github.com/Postgres-Extensions/object_reference/",
             "type": "git"
         }
     },
@@ -76,11 +76,12 @@
 
         "build": {
             "requires": {
-                "PostgreSQL": "9.5.0"
+                "PostgreSQL": "12.0.0"
             }
         },
         "runtime": {
             "requires": {
+                "cat_tools": 0,
                 "plpgsql": 0
             }
         },
@@ -95,7 +96,7 @@
     "no_index": "",
 
     "X_comment": "Unusual. Package/tool used to generate this file.",
-    "generated_by": "pgxntool https://github.com/decibel/pgxntool",
+    "generated_by": "pgxntool https://github.com/Postgres-Extensions/pgxntool",
 
     "X_comment": "REQUIRED. Version info for this file. http://pgxn.org/spec/#meta-spec",
     "meta-spec": {

META.json

@@ -9,7 +9,7 @@
     "X_comment": "Keys marked REQUIRED or Optional are what you'd expect. Keys marked Unusual are keys you don't normally need to use.",
     "X_comment": "The pgxntool Makefile will strip out empty keys to produce a working META.json, so it's fine to leave them here.",
     "X_comment": "NOTE: Don't get too cute with reformatting this file... some of the processing against it doesn't use a full JSON parser",
-    "X_comment": "I've tried to put things in a logical order. Comments welcome at https://github.com/decibel/pgxntool/issues!",
+    "X_comment": "I've tried to put things in a logical order. Comments welcome at https://github.com/Postgres-Extensions/pgxntool/issues!",
 
     "X_comment": "REQUIRED. Name of distribution.",
     "X_comment": "Note! Distribution names currently can't contain spaces.",
@@ -56,13 +56,13 @@
 
     "X_comment": "Optional. \"resources\": Web resources available for this distribution. http://pgxn.org/spec/#resources",
     "resources": {
-        "homepage": "http://github.com/decibel/object_reference/",
+        "homepage": "http://github.com/Postgres-Extensions/object_reference/",
         "bugtracker": {
-            "web": "http://github.com/decibel/object_reference/issues"
+            "web": "http://github.com/Postgres-Extensions/object_reference/issues"
         },
         "repository": {
-            "url": "git://github.com/decibel/object_reference.git",
-            "web": "http://github.com/decibel/object_reference/",
+            "url": "git://github.com/Postgres-Extensions/object_reference.git",
+            "web": "http://github.com/Postgres-Extensions/object_reference/",
             "type": "git"
         }
     },
@@ -74,11 +74,12 @@
 
         "build": {
             "requires": {
-                "PostgreSQL": "9.5.0"
+                "PostgreSQL": "12.0.0"
             }
         },
         "runtime": {
             "requires": {
+                "cat_tools": 0,
                 "plpgsql": 0
             }
         },
@@ -92,7 +93,7 @@
     "X_comment": "Unusual. \"no_index\": Files/directories that should not be indexed. http://pgxn.org/spec/#no_index",
 
     "X_comment": "Unusual. Package/tool used to generate this file.",
-    "generated_by": "pgxntool https://github.com/decibel/pgxntool",
+    "generated_by": "pgxntool https://github.com/Postgres-Extensions/pgxntool",
 
     "X_comment": "REQUIRED. Version info for this file. http://pgxn.org/spec/#meta-spec",
     "meta-spec": {