gh-39787:  Changed single colon to double colon after WARNING in relevant files
    
this PR fixes #39786
corrected the formatting of WARNING directives in the documentation. The
source code mistakenly used a single colon after WARNING instead of a
double colon.
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### ⌛ Dependencies

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URL: #39787
Reported by: Krishna Dubey
Reviewer(s): Frédéric Chapoton

Author: Release Manager

src/sage/algebras/cluster_algebra.py

@@ -1763,7 +1763,7 @@ def d_vector_to_g_vector(self, d) -> tuple:
 
             This method implements the piecewise-linear map `\\nu_c` introduced in Section 9.1 of [ReSt2020]_.
 
-        .. WARNING:
+        .. WARNING::
 
             This implementation works only when the initial exchange matrix is acyclic.
 
@@ -1789,7 +1789,7 @@ def g_vector_to_d_vector(self, g) -> tuple:
 
             This method implements the inverse of the piecewise-linear map `\\nu_c` introduced in Section 9.1 of [ReSt2020]_.
 
-        .. WARNING:
+        .. WARNING::
 
             This implementation works only when the initial exchange matrix is acyclic.
 

src/sage/combinat/sf/sfa.py

@@ -6492,7 +6492,7 @@ def __init__(self, basis, name, *args):
         - ``name`` -- the name of the basis
         - ``args`` -- any further arguments necessary to initialize the basis
 
-        .. WARNING:
+        .. WARNING::
 
             Strictly speaking, this is not necessarily a functor on
             :class:`CommutativeRings`, but rather a functor on
@@ -6632,7 +6632,7 @@ def __init__(self, basis, family, name, *args):
 
         - ``basis`` -- the basis of the symmetric function algebra
 
-        .. WARNING:
+        .. WARNING::
 
             Strictly speaking, this is not necessarily a functor on
             :class:`CommutativeRings`, but rather a functor on

src/sage/rings/function_field/drinfeld_modules/finite_drinfeld_module.py

@@ -571,7 +571,7 @@ def _frobenius_charpoly_gekeler(self):
         Instead, use :meth:`frobenius_charpoly` with the option
         `algorithm='gekeler'`.
 
-        .. WARNING:
+        .. WARNING::
 
             This algorithm only works in the generic case when the
             corresponding linear system is invertible. Notable cases

src/sage/rings/number_field/number_field_rel.py

@@ -38,7 +38,7 @@
     sage: a.parent()
     Number Field in sqrt2 with defining polynomial x^2 - 2 over its base field
 
-.. WARNING:
+.. WARNING::
 
     Doing arithmetic in towers of relative fields that depends on canonical
     coercions is currently VERY SLOW.  It is much better to explicitly coerce

src/sage/schemes/hyperelliptic_curves/jacobian_endomorphism_utils.py

@@ -62,7 +62,7 @@
     sage: A.geometric_endomorphism_algebra_is_field()
     False
 
-.. WARNING:
+.. WARNING::
 
     There is a very small chance that the algorithms return ``False`` for the
     two methods described above when in fact one or both of them are ``True``.