docs: clarify how to use JMeter with InfluxDB 2

[bednar]

Description

Improved documentation how to use JMeter with InfluxDB 2.

Motivation and Context

Clarifying to user that the JMeter support InfluxDB 2 and how to configure JMeter for that.

How Has This Been Tested?

Verified the generated JavaDoc and documentation.

Screenshots (if appropriate):

component_reference.html#Backend_Listener

Before:

After:

realtime-results.html

Before:

After:

package-summary.html

Before:

After:

InfluxdbBackendListenerClient.html

Before:

After:

Types of changes

• Documentation change

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly.

[codecov-io]

Codecov Report

Merging #588 into master will increase coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #588   +/-   ##
=========================================
  Coverage     55.31%   55.31%           
+ Complexity     9963     9962    -1     
=========================================
  Files          1032     1032           
  Lines         63371    63371           
  Branches       7159     7159           
=========================================
+ Hits          35051    35054    +3     
+ Misses        25842    25835    -7     
- Partials       2478     2482    +4     

Impacted Files	Coverage Δ	Complexity Δ
...ackend/influxdb/InfluxdbBackendListenerClient.java	39.55% <ø> (ø)	12.00 <0.00> (ø)
...a/org/apache/jmeter/timers/PoissonRandomTimer.java	72.97% <0.00%> (-5.41%)	9.00% <0.00%> (-1.00%)
...ache/jmeter/reporters/SummariserRunningSample.java	83.58% <0.00%> (-1.50%)	18.00% <0.00%> (-1.00%)
...n/java/org/apache/jmeter/reporters/Summariser.java	84.73% <0.00%> (-0.77%)	17.00% <0.00%> (-1.00%)
...main/java/org/apache/jorphan/gui/MenuScroller.java	34.73% <0.00%> (+4.19%)	10.00% <0.00%> (+2.00%)

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[FSchumacher]

Thanks for the contribution. I hope you didn't mind my changes.

[bednar]

Thank you @FSchumacher