copy subset of Sprig template functions

docs/sprig/reflection.md

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+# Reflection Functions
+
+Sprig provides rudimentary reflection tools. These help advanced template
+developers understand the underlying Go type information for a particular value.
+
+Go has several primitive _kinds_, like `string`, `slice`, `int64`, and `bool`.
+
+Go has an open _type_ system that allows developers to create their own types.
+
+Sprig provides a set of functions for each.
+
+## Kind Functions
+
+There are two Kind functions: `kindOf` returns the kind of an object.
+
+```
+kindOf "hello"
+```
+
+The above would return `string`. For simple tests (like in `if` blocks), the
+`kindIs` function will let you verify that a value is a particular kind:
+
+```
+kindIs "int" 123
+```
+
+The above will return `true`
+
+## Type Functions
+
+Types are slightly harder to work with, so there are three different functions:
+
+- `typeOf` returns the underlying type of a value: `typeOf $foo`
+- `typeIs` is like `kindIs`, but for types: `typeIs "*io.Buffer" $myVal`
+- `typeIsLike` works as `typeIs`, except that it also dereferences pointers.
+
+**Note:** None of these can test whether or not something implements a given
+interface, since doing so would require compiling the interface in ahead of time.
+
+## deepEqual
+
+`deepEqual` returns true if two values are ["deeply equal"](https://golang.org/pkg/reflect/#DeepEqual)
+
+Works for non-primitive types as well (compared to the built-in `eq`).
+
+```
+deepEqual (list 1 2 3) (list 1 2 3)
+```
+
+The above will return `true`