Revert "C++: Revert doc-related changes to dbscheme"

This reverts commit e81d197.

Author: geoffw0

cpp/ql/src/semmlecode.cpp.dbscheme

@@ -239,7 +239,7 @@ svnchurn(
  * The location spans column `startcolumn` of line `startline` to
  * column `endcolumn` of line `endline` in file `file`.
  * For more information, see
- * [LGTM locations](https://lgtm.com/docs/ql/locations).
+ * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
  */
 locations_default(
     /** The location of an element that is not an expression or a statement. */
@@ -256,7 +256,7 @@ locations_default(
  * The location spans column `startcolumn` of line `startline` to
  * column `endcolumn` of line `endline` in file `file`.
  * For more information, see
- * [LGTM locations](https://lgtm.com/docs/ql/locations).
+ * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
  */
 locations_stmt(
     /** The location of a statement. */
@@ -273,7 +273,7 @@ locations_stmt(
  * The location spans column `startcolumn` of line `startline` to
  * column `endcolumn` of line `endline` in file `file`.
  * For more information, see
- * [LGTM locations](https://lgtm.com/docs/ql/locations).
+ * [Locations](https://help.semmle.com/QL/learn-ql/ql/locations.html).
  */
 locations_expr(
     /** The location of an expression. */