Docs – jar install page and getCallerClass error (#19018)

* added links and edited headings

* documented getCallerClass error

* Added create directory section

* Wording and spacing edits per Jeff feedback

* Fixing error in ToC from last commit

* punctuation and spacing

Co-authored-by: ft-metabase <ft-metabase@ft-metabases-MacBook-Pro.local>
Co-authored-by: Jeff Bruemmer <jeff@metabase.com>

docs/operations-guide/running-the-metabase-jar-file.md

@@ -2,15 +2,19 @@
 
 To run Metabase via a JAR file, you will need to have a Java Runtime Environment (JRE) installed on your system.
 
-### Install Java JRE
+## Install Java JRE
 
 We recommend the latest LTS version of JRE from [AdoptOpenJDK](https://adoptopenjdk.net/releases.html) with HotSpot JVM and x64 architecture, but other [Java versions](./java-versions.md) are supported too.
 
-### Download Metabase
+## Download Metabase
 
-Go to the [Metabase download page](https://metabase.com/start/jar.html) and download the latest release. Place the downloaded JAR file into a newly created directory (as it will create some files when it is run).
+Go to the [Metabase download page](https://metabase.com/start/jar.html) and download the latest release. 
 
-### Launching Metabase
+## Create a new directory and move the JAR into it
+
+The JAR file will create some new files when it is run, so it's important to have a dedicated directory for it. Don't just leave it in your Downloads directory.
+
+## Launching Metabase
 
 Now that you have Java working you can run the JAR from a terminal with:
 
@@ -29,8 +33,16 @@ It's that simple. This will start the Metabase application using all of the defa
 
 At this point you're ready to go! You can access your new Metabase server on port 3000, most likely at [http://localhost:3000](http://localhost:3000)
 
-You can use another port than 3000 by setting the `MB_JETTY_PORT` environment variable before running the jar.
+You can use another port than 3000 by setting the `MB_JETTY_PORT` [environment variable](./environment-variables.md) before running the jar.
 
 Note that in the default configuration Metabase will use a local H2 database for storing all its own application data. This is meant for simple evaluations or personal use, so if you want to run Metabase in production we recommend you [migrate away from H2](./migrating-from-h2.md).
 
+## Troubleshooting
+
+If you run into any problems during installation, check out our [troubleshooting page](../troubleshooting-guide/running.md).
+
+## Continue to setup
+
 Now that you’ve installed Metabase, it’s time to [set it up and connect it to your database](../setting-up-metabase.md).
+
+

docs/troubleshooting-guide/running.md

 # Running Metabase
 
 <div class='doc-toc' markdown=1>
+- [WARNING: sun.reflect.Reflection.getCallerClass is not supported](#warning-sunreflectreflectiongetcallerclass-is-not-supported)
 - [Metabase fails to start due to Heap Space OutOfMemoryErrors](#heap-space-outofmemoryerrors)
 - [Diagnosing memory issues causing OutOfMemoryErrors](#diagnosing-outofmemoryerrors)
 - [Metabase cannot read or write from a file or folder (IOError)](#cannot-read-write-ioerror)
@@ -8,6 +9,16 @@
 
 Metabase runs on the Java Virtual Machine (JVM), and depending on how it's configured, it may use the server's filesystem to store some information. Problems with either the JVM or the filesystem can therefore prevent Metabase from running.
 
+<h2 id="warning-sunreflectreflectiongetcallerclass-is-not-supported">WARNING: sun.reflect.Reflection.getCallerClass is not supported.</h2>
+
+Don't worry about it. 
+
+``` 
+WARNING: sun.reflect.Reflection.getCallerClass is not supported. This will impact performance.
+```
+
+If you see the above error, ignore it. Your Metabase is perfectly healthy and performing as it should.
+
 <h2 id="heap-space-outofmemoryerrors">Metabase fails to start due to Heap Space OutOfMemoryErrors</h2>
 
 The JVM can normally figure out how much RAM is available on the system and automatically set a sensible upper bound for heap memory usage. On certain shared hosting environments, however, this doesn't always work as desired. The usual symptom of this is an error message like: