Reference the root requirements from the insiders requirements file (#5105)

Seems best not to duplicate these

docs/requirements-insiders.in

@@ -1,7 +1,2 @@
-black>=23.10.0
+-r requirements.in
-mkdocs>=1.5.0
 mkdocs-material @ git+ssh://git@github.com/astral-sh/mkdocs-material-insiders.git@38c0b8187325c3bab386b666daf3518ac036f2f4
-mkdocs-redirects>=1.2.1
-mdformat>=0.7.17
-mdformat-mkdocs>=2.0.4
-mdformat-admon>=2.0.2

docs/requirements-insiders.txt

@@ -3,7 +3,7 @@
 babel==2.15.0
     # via mkdocs-material
 black==23.10.0
-    # via -r docs/requirements-insiders.in
+    # via -r docs/requirements.in
 certifi==2024.7.4
     # via requests
 charset-normalizer==3.3.2
@@ -43,19 +43,19 @@ markupsafe==2.1.5
     #   mkdocs
 mdformat==0.7.17
     # via
-    #   -r docs/requirements-insiders.in
+    #   -r docs/requirements.in
     #   mdformat-admon
     #   mdformat-gfm
     #   mdformat-mkdocs
     #   mdformat-tables
 mdformat-admon==2.0.2
     # via
-    #   -r docs/requirements-insiders.in
+    #   -r docs/requirements.in
     #   mdformat-mkdocs
 mdformat-gfm==0.3.6
     # via mdformat-mkdocs
 mdformat-mkdocs==2.0.4
-    # via -r docs/requirements-insiders.in
+    # via -r docs/requirements.in
 mdformat-tables==0.4.1
     # via mdformat-gfm
 mdit-py-plugins==0.4.1
@@ -70,15 +70,17 @@ mergedeep==1.3.4
     #   mkdocs-material
 mkdocs==1.5.0
     # via
-    #   -r docs/requirements-insiders.in
+    #   -r docs/requirements.in
     #   mkdocs-material
     #   mkdocs-redirects
 mkdocs-material @ git+ssh://git@github.com/astral-sh/mkdocs-material-insiders.git@38c0b8187325c3bab386b666daf3518ac036f2f4
-    # via -r docs/requirements-insiders.in
+    # via
+    #   -r docs/requirements-insiders.in
+    #   -r docs/requirements.in
 mkdocs-material-extensions==1.3.1
     # via mkdocs-material
 mkdocs-redirects==1.2.1
-    # via -r docs/requirements-insiders.in
+    # via -r docs/requirements.in
 more-itertools==10.3.0
     # via mdformat-mkdocs
 mypy-extensions==1.0.0