add functions help

resources/function_help/json/CRS

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+{
+  "name": "CRS",
+  "type": "group",
+  "description": "This group contains functions to operate on coordinate reference system objects."
+}

resources/function_help/json/crs_authid

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+{
+  "name": "crs_authid",
+  "type": "function",
+  "groups": ["CRS"],
+  "description": "Returns a user-friendly identifier for the CRS",
+  "arguments": [{
+    "arg": "crs",
+    "description": "crs value"
+  }],
+  "examples": [{
+    "expression": "crs_authid(make_crs('EPSG:3857'))",
+    "returns": "'EPSG:3857'"
+  }],
+  "tags": ["crs", "epsg", "authid"]
+}

resources/function_help/json/make_crs

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+{
+  "name": "make_crs",
+  "type": "function",
+  "groups": ["CRS"],
+  "description": "Creates a coordinate reference system from a string definition",
+  "arguments": [{
+    "arg": "definition",
+    "description": "CRS definition"
+  }],
+  "examples": [{
+    "expression": "make_crs('EPSG:3857')",
+    "returns": "crs value 'EPSG:3857 - WGS 84 / Pseudo-Mercator'"
+  }],
+  "tags": ["crs", "epsg"]
+}