Add basic rule description

rules/S2253/cfamily/metadata.json

@@ -1,2 +1,3 @@
 {
+    "title": "User-specified functions should not be called"
 }

rules/S2253/cfamily/rule.adoc

@@ -1,44 +1,19 @@
-FIXME: add a description
+This rule template allows to define rules that ban the call of some functions, for instance functions provided for legacy reasons. It will not prevent calling member functions or macros with the same name.
 
-// If you want to factorize the description uncomment the following line and create the file.
-//include::../description.adoc[]
+=== Noncompliant code example
 
-== Why is this an issue?
+Given parameters:
 
-FIXME: remove the unused optional headers (that are commented out)
+* names: f1, ::f2
+* message: Don't call $
 
-//=== What is the potential impact?
-
-== How to fix it
-//== How to fix it in FRAMEWORK NAME
-
-=== Code examples
-
-==== Noncompliant code example
-
-[source,cpp,diff-id=1,diff-type=noncompliant]
-----
-FIXME
-----
-
-==== Compliant solution
-
-[source,cpp,diff-id=1,diff-type=compliant]
+[source,cpp]
 ----
-FIXME
+void f() {
+  f1(); // Noncompliant: Don't call f1
+  my::f1(); // Noncompliant: Don't call f1
+  f2(); // Noncompliant: Don't call f2
+  my::f2() // Compliant
+}
 ----
 
-//=== How does this work?
-
-//=== Pitfalls
-
-//=== Going the extra mile
-
-
-//== Resources
-//=== Documentation
-//=== Articles & blog posts
-//=== Conference presentations
-//=== Standards
-//=== External coding guidelines
-//=== Benchmarks