Added chapter about generating qhelp files locally

Author: timoles

docs/query-help-style-guide.md

@@ -110,6 +110,18 @@ For example:
 
 If your query checks code for a CWE weakness, you should use the `@tags` element in the query file to reference the associated CWEs, as explained [here](query-metadata-style-guide.md). When you use these tags, a link to the appropriate entry from the [MITRE.org](https://cwe.mitre.org/scoring/index.html) site will automatically appear as a reference in the output HTML file.
 
+## Validating qhelp files
+
+Before making a pull request you should ensure the `.qhelp` file is well-formed and can be generated without problems. For example, this can be done locally with `codeql-cli` tool. In order to do so just start the `codeql-cli` with the appropriate parameters, as seen in the following example:
+
+```bash
+# codeql generate query-help <path_to_your_qhelp_file> --format=<format>
+# For example:
+codeql generate query-help ./myCustomQuery.qhelp --format=markdown
+```
+
+More information on how to test your `.qhelp` files can be found [within the documentation](https://codeql.github.com/docs/codeql-cli/testing-query-help-files/)
+
 ## Query help example
 
 The following example is a query help file for a query from the standard query suite for Java: