[web] Refined wording on XSD error page.

web/content/docs/userguide/troubleshooting/index.md

@@ -14,6 +14,8 @@ toc = true
 
 ### XSDError: Loaded schema file is invalid
 
+You may encountering the following error (or similar) on opening `.gml`, `.cnd`, `std` or `.prj` files in the Data Explorer or file conversion tools (e.g. `OGSFileConverter`):
+
 <i class="fas fa-exclamation-triangle"></i> Error message:
 
 ```bash
@@ -23,11 +25,9 @@ XMLInterface::isValid() - XML File is invalid (in reference to schema ./OpenGeoS
 Error XSDError in http://www.opengeosys.org/images/xsd/OpenGeoSysCND.xsd, at line 1, column 1: Start tag expected.
 ```
 
-This error may also apply to file conversion tools (e.g. `OGSFileConverter`).
-
 <i class="fas fa-arrow-right"></i> Solution:
 
-Open the affected file (e.g. `well.cnd` in this case) and remove the following parameter of the XML root element:
+Open the affected file (e.g. `well.cnd` in this case) in a text editor and remove the following parameter of the XML root element (the first element in `< >`-brackets in the element, e.g. `<OpenGeoSysCND>`):
 
 ```xml
 xsi:noNamespaceSchemaLocation="http://www.opengeosys.org/images/xsd/OpenGeoSysXXX.xsd"
@@ -35,6 +35,8 @@ xsi:noNamespaceSchemaLocation="http://www.opengeosys.org/images/xsd/OpenGeoSysXX
 
 where `XXX` can be `CND`, `GLI`, `PRJ` or `STN` depending on the file type.
 
+Now the save the modified file and try to load it again.
+
 <details>
     <summary>Background info:</summary>
     The XSD files may be downloaded from a web location. We changed the protocol of our web site to `https://` but due to some weird behaviour of the Qt XML validation code it tries to download the file (even if it is available locally) and does not respect the URL redirection to `https://` of the web server. Simply removing the part solves the problem. The XML is still validated! Newer OGS versions do not write that parameter into files anymore, see https://github.com/ufz/ogs/pull/2198.