Adding some impl crumbs to docstrings (#1508)

Author: john-science

armi/nuclearDataIO/xsCollections.py

@@ -381,6 +381,7 @@ def __init__(
     def createMacrosOnBlocklist(
         self, microLibrary, blockList, nucNames=None, libType="micros"
     ):
+        """Create macroscopic cross sections for a list of blocks."""
         for block in blockList:
             block.macros = self.createMacrosFromMicros(
                 microLibrary, block, nucNames, libType=libType
@@ -788,6 +789,10 @@ def computeMacroscopicGroupConstants(
     """
     Compute any macroscopic group constants given number densities and a microscopic library.
 
+    .. impl:: Compute macroscopic cross sections from microscopic cross sections and number densities.
+        :id: I_ARMI_NUCDATA_MACRO
+        :implements: R_ARMI_NUCDATA_MACRO
+
     Parameters
     ----------
     constantName : str

armi/physics/neutronics/macroXSGenerationInterface.py

@@ -144,6 +144,10 @@ def buildMacros(
         Builds G-vectors of the basic XS ('nGamma','fission','nalph','np','n2n','nd','nt')
         Builds GxG matrices for scatter matrices
 
+        .. impl:: Build macroscopic cross sections for blocks.
+            :id: I_ARMI_MACRO_XS
+            :implements: R_ARMI_MACRO_XS
+
         Parameters
         ----------
         lib : library object , optional

armi/reactor/blocks.py

@@ -1561,6 +1561,10 @@ def rotate(self, rad):
     def setAxialExpTargetComp(self, targetComponent):
         """Sets the targetComponent for the axial expansion changer.
 
+        .. impl:: Set the target axial expansion components on a given block.
+            :id: I_ARMI_MANUAL_TARG_COMP
+            :implements: R_ARMI_MANUAL_TARG_COMP
+
         Parameter
         ---------
         targetComponent: :py:class:`Component <armi.reactor.components.component.Component>` object