Add diagram containing decimal and integer conversion overview (#225)

Author: webmaster128

public/actor-model.svg public/diagrams/actor-model.svgpublic/actor-model.svg renamed to public/diagrams/actor-model.svg

@@ -35,7 +35,7 @@ rummage around in their belongings (state). They simply exchange messages and pu
 other side needs to know into a message.
 
 <Image
-  src="/actor-model.svg"
+  src="/diagrams/actor-model.svg"
   alt="Actor model"
   style={{ marginTop: "1em", marginBottom: "1em" }}
   width={1920}

public/diagrams/integer-decimal-conversions.png

@@ -7,5 +7,25 @@ import { Callout } from "nextra/components";
 # Math
 
 CosmWasm offers mathematical primitives for, you guessed it, mathematical operations. In contrast to
-the Rust standard library, which is limited to 128 bit integers, we offer integers that exceed that
-precision.
+the Rust standard library, which is limited to 128 bit integers, we offer [integers] that exceed
+that precision. Also [decimals] for fixed point math are available.
+
+## Conversions
+
+The following overview shows how to convert between integers and decimals of different size. This
+only shows the unsigned case but the signed types work the same way.
+
+![Integer decimal conversions overview](/diagrams/integer-decimal-conversions.png)
+
+<>
+  {/* The diagram is maintained in Simon's personal Google account
+  https://drive.google.com/file/d/17NQHkUTOgmFcxE8_DcH3yFlAw-mQjyG8/view?usp=sharing */}
+</>
+
+`From`/`TryFrom` refer to the
+[Rust trait implementations](https://doc.rust-lang.org/rust-by-example/conversion/from_into.html).
+`::to_*` are functions on the source type and `::new`/`::from_*` are functions on the destination
+type.
+
+[integers]: ./math/integers
+[decimals]: ./math/decimals