docs: make plugin authoring a first-class, accurate workflow

examples/plugins/wasm/plugin.manifestadded+17-0

Changes to examples/plugins/wasm/plugin.manifest

		@@ -0,0 +1,17 @@
	1	+# Den plugin manifest (key = value).
	2	+# Placed next to a plugin so Den can describe it without loading code.
	3	+# Lines starting with '#' and blank lines are ignored.
	4	+
	5	+name = math
	6	+version = 1.0.0
	7	+description = Example WebAssembly plugin exposing add, mul and fib
	8	+author = Den
	9	+license = MIT
	10	+
	11	+# Minimum Den version this plugin targets (optional).
	12	+min_shell_version = 0.1
	13	+
	14	+# Dependencies (optional, repeatable):
	15	+# dependency = <name>:<version-req>
	16	+# dependency = <name>:<version-req>:optional
	17	+# (none for this example)