added readme about adding an api call to the sdk

Author: THeflinKeeper

README.md

@@ -39,3 +39,35 @@ npm link ../../keeperapi
 ```
 
 from your client folder
+
+How to add an api command to this sdk:
+
+Prerequisites: 
+- Have the keeperapp-protobuf repo alongside this repo (eg: /home/keeper-sdk-javascript and /home/keeperapp-protobuf)
+- Make sure that the protobuf that you want is in the branch of the keeperapp-protobuf project you have loaded
+- In the update-proto:cjs and update-proto:es6 commands in keeperapi/package.json, ensure that the proto files from keeperapp-protobuf that you want are listed there
+
+Steps:
+1. Navigate to the keeperapi folder in your terminal (eg: /home/keeper-sdk-javascript/keeperapi)
+2. Run command ```npm run update-proto:cjs``` then command ```npm run update-proto:es6```
+3. Open the file ```keeperapi/src/restMessages.ts```
+4. There are 4 messages we handle with each of their differences:
+    a. createInMessage - This expects data to be sent
+    b. createOutMessage - This expects data to be received
+    c. createMessage - This expects data to be sent and received
+    d. createActionMessage - This expects no data sent or received, just make the call
+
+5. In the file, you will see various examples of each of those 4 messages being used. Their typical layout is as follows:
+    a. createInMessage: export const name = (data: requestType): RestInMessage<requestType> =>
+    createInMessage(data, 'api/call', requestType)
+    b. createOutMessage: export const name = (): RestOutMessage<responseType> =>
+    createOutMessage('api/call', responseType)
+    c. createMessage: export const name = (data: requestType): RestMessage<requestType, responseType> =>
+    createMessage(data, 'api/call', requestType, responseType)
+    d. createActionMessage: export const name = (): RestActionMessage => createActionMessage('api/call')
+
+6. From the examples, here are the variables and where you can get them:
+- name: This is from the api url mostly. This can be named whatever as long as it makes sense
+- requestType: This will be given from the loaded protobuf
+- responseType: Same with requestType
+- 'api/call': This is the path of the api url in string form. This needs to be a string