Remove concatenation syntax in favor of interpolation/substitution

Author: bjuric

docs/11-advanced/08-string-interpolation.mdx

@@ -13,7 +13,7 @@ import useBaseUrl from '@docusaurus/useBaseUrl';
 It is often useful to reference provided properties, captured values, and string literals throughout your features. Gwen provides two interpolation mechanisms for doing this:
 
 - [Substitution](#interpolation-by-substitution) (recommended approach)
-- [Concatenation](#interpolation-by-concatenation)
+- [Concatenation](#interpolation-by-concatenation) (deprecated since [Gwen 3](/docs/gwen3))
 
 Interpolation occurs in the interpreter on every step in a feature before it is passed to Gwen for execution.
 
@@ -56,6 +56,12 @@ Scenario: By Substitution
 
 ### Interpolation by Concatenation
 
+:::caution Deprecated
+
+The concatentation method has been deprecated in favor of substitition since [Gwen 3](/docs/gwen3) (dropped in <Link to="https://github.com/gwen-interpreter/gwen-web/releases/tag/v3.14.0">v3.14.0</Link>)
+
+:::
+
 Concatenation involves joining string literals and named values together.
 
 ```gherkin

docs/14-gwen3/01-gwen3.mdx

@@ -69,6 +69,7 @@ The embedded web engine now  uses Selenium 4 and new DSLs have been added to sup
 
 - Gwen workspaces have been deprecated in favor of JS projects
 - Applitools integration has been removed
+- [Interpolation](/docs/advanced/string-interpolation#interpolation-by-substitution) by concatenation deprecated in favor of substitation (dropped in <Link to="https://github.com/gwen-interpreter/gwen-web/releases/tag/v3.14.0">v3.14.0</Link>)
 
 ## Migration guide
 

package.json

@@ -14,8 +14,8 @@
     "write-heading-ids": "docusaurus write-heading-ids"
   },
   "dependencies": {
-    "@docusaurus/core": "^2.0.0-beta.20",
-    "@docusaurus/preset-classic": "^2.0.0-beta.20",
+    "@docusaurus/core": "^2.0.0-beta.21",
+    "@docusaurus/preset-classic": "^2.0.0-beta.21",
     "@mdx-js/react": "^1.6.21",
     "@svgr/webpack": "^5.5.0",
     "clsx": "^1.1.1",