Add experimental remark to AsciiDoc reporter description

Signed-off-by: Johannes Thorn <2544827+johthor@users.noreply.github.com>

docs/report_generation.adoc

@@ -80,11 +80,16 @@ https://jgiven.org/jgiven-report/html5/[HTML report of JGiven itself]
 
 === AsciiDoc Report
 
+[CAUTION]
+====
+The generator for AsciiDoc reports is currently still in an experimental phase.
+Not all functions of the HTML report are supported.
+====
+
 To generate an AsciiDoc report you have to run the JGiven report generator with the `asciidoc` format option.
 The report generator can be executed on the command line as follows
 (assuming that the `jgiven-core` JAR and all required dependencies are on the Java CLASSPATH)
 
-
 [source,console]
 ----
 $ java com.tngtech.jgiven.report.ReportGenerator \
@@ -126,32 +131,38 @@ For Maven there exists a plugin that can be used as follows:
 You can add the following configuration options (like the _format_ configuration above) to customize the report.
 All of them are optional.
 
-[cols="1,3"]
+[%autowidth]
 .Configuration Options for Reports
 |===
-|Option |Description
+|Option |Default value |Description
 
 |format
-|The format of the generated report. Can be _html_, _text_ or _asciidoc_. Default: _html_
+|`html`
+|The format of the generated report. Can be _html_, _text_ or _asciidoc_.
 
 |title
-|The title of the generated report. Default: _JGiven Report_
+|`JGiven Report`
+|The title of the generated report.
 
 |customCssFile
-|Custom CSS file to customize the HTML report. Default: _src/test/resources/jgiven/custom.css_
+|`src/test/resources/jgiven/custom.css`
+|Custom CSS file to customize the HTML report.
 
 |customJsFile
-|Custom JS file to customize the HTML report. Default: _src/test/resources/jgiven/custom.js_
+|`src/test/resources/jgiven/custom.js`
+|Custom JS file to customize the HTML report.
 
 |excludeEmptyScenarios
-|Whether or not to exclude empty scenarios, i.e. scenarios without any steps, from the report. Default: _false_
+|`false`
+|Whether or not to exclude empty scenarios, i.e. scenarios without any steps, from the report.
 
 |outputDirectory
-|Directory where the reports are generated to. Default: _${project.build.directory}/jgiven-reports/html_
+|`${project.build.directory}/jgiven-reports/html`
+|Directory where the reports are generated to.
 
 |sourceDirectory
-|Directory to read the JSON report files from. Default: _${project.build.directory}/jgiven-reports/json_
-
+|`${project.build.directory}/jgiven-reports/json`
+|Directory to read the JSON report files from.
 |===
 
 Now run: