Docs: Include internal cmds in toctree

Also fixing some missing refs (using single backticks instead of double).

docs/source/cmd/index_internal.rst

@@ -1,5 +1,3 @@
-:orphan:
-
 Internal commands for developers
 --------------------------------
 

docs/source/cmd_ref.rst

@@ -27,9 +27,7 @@ Command reference
    /cmd/index_passes
    /cmd/index_techlibs
 
-.. TODO:: Fix index_internal not being included in pdf
+.. toctree::
+   :maxdepth: 2
 
-.. note::
-
-   Commands intended for internal developer use can also be found under
-   :doc:`/cmd/index_internal`
+   /cmd/index_internal

docs/source/yosys_internals/hashing.rst

@@ -138,7 +138,7 @@ Previously, the interface to implement hashing on custom types was just
 independently and then ad-hoc combined with the hash function with some xorshift
 operations thrown in to mix bits together somewhat. A plugin can stay compatible
 with both versions prior and after the break by implementing both interfaces
-based on the existance and value of `YS_HASHING_VERSION`.
+based on the existance and value of ``YS_HASHING_VERSION``.
 
 .. code-block:: cpp
    :caption: Example hash compatibility wrapper

docs/source/yosys_internals/verilog.rst

@@ -96,7 +96,7 @@ Verilog Attributes and non-standard features
 - The ``keep_hierarchy`` attribute on cells and modules keeps the `flatten`
   command from flattening the indicated cells and modules.
 
-- The `gate_cost_equivalent` attribute on a module can be used to specify
+- The ``gate_cost_equivalent`` attribute on a module can be used to specify
   the estimated cost of the module as a number of basic gate instances. See
   the help message of command `keep_hierarchy` which interprets this
   attribute.