Add syntax highlighting in Readme and fix a couple typos

Typos:
- Add missing "\" at line end
- Remove stray "`" at line end

Author: jordan-brough

README.md

@@ -79,7 +79,7 @@ You can build RIE into a base image. Download the RIE from GitHub to your local
 
     The following example shows a typical script for a Node.js function.
 
-    ```
+    ```sh
     #!/bin/sh
     if [ -z "${AWS_LAMBDA_RUNTIME_API}" ]; then
       exec /usr/local/bin/aws-lambda-rie /usr/bin/npx aws-lambda-ric
@@ -93,28 +93,24 @@ You can build RIE into a base image. Download the RIE from GitHub to your local
 3. Install the emulator package and change `ENTRYPOINT` to run the new script by adding the following lines to your Dockerfile:
 
     To use the default x86\_64 architecture
-
-    ```
+    ```dockerfile
     ADD aws-lambda-rie /usr/local/bin/aws-lambda-rie
     ENTRYPOINT [ "/entry_script.sh" ]
     ```
 
     To use the arm64 architecture:
-
-    ```
+    ```dockerfile
     ADD aws-lambda-rie-arm64 /usr/local/bin/aws-lambda-rie
     ENTRYPOINT [ "/entry_script.sh" ]
     ```
 
 4. Build your image locally using the docker build command.
-
-    ```
+    ```sh
     docker build -t myfunction:latest .
     ```
 
 5. Run your image locally using the docker run command.
-
-    ```
+    ```sh
     docker run -p 9000:8080 myfunction:latest
     ```
 
@@ -125,7 +121,7 @@ You install the runtime interface emulator to your local machine. When you run t
 
 1. From your project directory, run the following command to download the RIE (x86-64 architecture) from GitHub and install it on your local machine.
 
-    ```
+    ```sh
     mkdir -p ~/.aws-lambda-rie && curl -Lo ~/.aws-lambda-rie/aws-lambda-rie \
     https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie \
     && chmod +x ~/.aws-lambda-rie/aws-lambda-rie
@@ -138,17 +134,18 @@ You install the runtime interface emulator to your local machine. When you run t
     ```
 
 2. Run your Lambda image function using the docker run command.
-
-    ```
-    docker run -d -v ~/.aws-lambda-rie:/aws-lambda -p 9000:8080 myfunction:latest
-        --entrypoint /aws-lambda/aws-lambda-rie  <image entrypoint> <(optional) image command>`
+    ```sh
+    docker run -d -v ~/.aws-lambda-rie:/aws-lambda -p 9000:8080 myfunction:latest \
+        --entrypoint /aws-lambda/aws-lambda-rie  <image entrypoint> <(optional) image command>
     ```
 
     This runs the image as a container and starts up an endpoint locally at `localhost:9000/2015-03-31/functions/function/invocations`.
 
 3. Post an event to the following endpoint using a curl command:
 
-    `curl -XPOST "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'`
+    ```sh
+    curl -XPOST "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'
+    ```
 
     This command invokes the function running in the container image and returns a response.