add help docs and ?

docs/nodes/Number.md

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+# Number
+
+Output a fixed numeric value. When connected to FLOAT inputs the exact value is used; INT inputs round to the nearest integer at execution time.
+
+## Inputs
+
+None.
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| value | FLOAT | The numeric value set by the widget |
+
+## Controls
+
+| Name | Type | Default | Description |
+|------|------|---------|-------------|
+| value | FLOAT | 0.0 | The numeric value to output |
+
+## Limitations
+
+- None.