doc: move application development section

Move application development docs into the new `developing with zephyr`
section.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/doc/application/application-kconfig.include b/doc/develop/application/application-kconfig.include
similarity index 100%
rename from doc/application/application-kconfig.include
rename to doc/develop/application/application-kconfig.include
diff --git a/doc/application/index.rst b/doc/develop/application/index.rst
similarity index 100%
rename from doc/application/index.rst
rename to doc/develop/application/index.rst
diff --git a/doc/develop/index.rst b/doc/develop/index.rst
index 908939e..89908b0 100644
--- a/doc/develop/index.rst
+++ b/doc/develop/index.rst
@@ -8,5 +8,6 @@
 
    getting_started/index.rst
    beyond-GSG.rst
+   application/index.rst
    modules.rst
    west/index
diff --git a/doc/index-tex.rst b/doc/index-tex.rst
index dea5549..1c06a8b 100644
--- a/doc/index-tex.rst
+++ b/doc/index-tex.rst
@@ -21,7 +21,6 @@
    connectivity/index.rst
    services/index.rst
    development_process/index.rst
-   application/index.rst
    reference/index.rst
    guides/index.rst
    security/index.rst
diff --git a/doc/index.rst b/doc/index.rst
index 72fd1c1..1fc26f3 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -105,7 +105,6 @@
    develop/index.rst
    contribute/index.rst
    development_process/index.rst
-   application/index.rst
    build/index.rst
    kernel/index.rst
    connectivity/index.rst