Improve math docs (#24)

Fix some small issues, like the outdated module description mentioning
it is internal, which is not true anymore. Also, fix some capitalization
issues in the docstrings.

Author: llucax

src/frequenz/core/math.py

@@ -1,7 +1,7 @@
 # License: MIT
 # Copyright © 2023 Frequenz Energy-as-a-Service GmbH
 
-"""Internal math tools."""
+"""Math tools."""
 
 import math
 
@@ -15,11 +15,11 @@ def is_close_to_zero(value: float, abs_tol: float = 1e-9) -> bool:
     For more technical details, see https://peps.python.org/pep-0485/#behavior-near-zero
 
     Args:
-        value: the floating point value to compare to.
-        abs_tol: the minimum absolute tolerance. Defaults to 1e-9.
+        value: The floating point value to compare to.
+        abs_tol: The minimum absolute tolerance. Defaults to 1e-9.
 
     Returns:
-        whether the floating point value is close to zero.
+        Whether the floating point value is close to zero.
     """
     zero: float = 0.0
     return math.isclose(a=value, b=zero, abs_tol=abs_tol)