Fix #1863: Add getHashUpgrades hacknet function

Adds a new functions ofr hacknet servers that returns the list of
available hash upgrades.

markdown/bitburner.hacknet.gethashupgrades.md

@@ -0,0 +1,34 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [bitburner](./bitburner.md) &gt; [Hacknet](./bitburner.hacknet.md) &gt; [getHashUpgrades](./bitburner.hacknet.gethashupgrades.md)
+
+## Hacknet.getHashUpgrades() method
+
+Get the list of hash upgrades
+
+<b>Signature:</b>
+
+```typescript
+getHashUpgrades(): string[];
+```
+<b>Returns:</b>
+
+string\[\]
+
+An array containing the available upgrades
+
+## Remarks
+
+RAM cost: 0 GB
+
+This function is only applicable for Hacknet Servers (the upgraded version of a Hacknet Node).
+
+Returns the list of all available hash upgrades that can be used in the spendHashes function.
+
+## Example
+
+
+```ts
+const upgrades = hacknet.getHashUpgrades(); // ["Sell for Money","Sell for Corporation Funds",...]
+```
+