doc: rename lxsocdoc -> socdoc and update readme

With the merge of lxsocdoc into upstream litex, the old name of
"lxsocdoc" doesn't make as much sense.  Additionally, the import paths
are now different.

Rename this file to reflect the new home of `soc/doc`, and update the
code examples to work with the new name.

Signed-off-by: Sean Cross <sean@xobs.io>

doc/socdoc.md

@@ -1,6 +1,6 @@
-# lxsocdoc: Document your LiteX SoC Automatically
+# Litex Documentation: Document your LiteX SoC Automatically
 
-`lxsocdoc` lets you take a synthesized LiteX SoC and generate full
+Litex lets you take a synthesized SoC and generate full
 register-level documentation.  Additionally, it will generate `.svd` files,
 suitable for use with various header generation programs.
 
@@ -15,19 +15,19 @@ $ pip3 install sphinxcontrib-wavedrom sphinx
 
 ## Usage
 
-To use `lxsocdoc`, import the module and call `lxsocdoc.generate_docs(soc, path)`.
+To document your modules, import the `doc` module and call `doc.generate_docs(soc, path)`.
 You can also generate an SVD file.  For example:
 
 ```python
-import lxsocdoc
+import litex.soc.doc
 
 ...
     soc = BaseSoC(platform)
     builder = Builder(soc)
     vns = builder.build()
     soc.do_exit(vns)
-    lxsocdoc.generate_docs(soc, "build/documentation")
-    lxsocdoc.generate_svd(soc, "build/software")
+    doc.generate_docs(soc, "build/documentation")
+    doc.generate_svd(soc, "build/software")
 ```
 
 After you build your design, you will have a Sphinx documentation source available
@@ -39,10 +39,7 @@ For example, if `sphinx-build` is in your path, you can run:
 
 `sphinx-build` may be located in `~/.local/bin/` depending on your installation environment.
 
-You can then verify the contents by starting a local webserver and opening a web
-browser to [localhost:8000](http://localhost:8000):
-
-`python3 -m http.server --directory build/documentation/_build/html`
+You can then verify the contents by opening the file `build/documentation/_build/html/index.html`
 
 ## Documenting your Registers
 
@@ -113,7 +110,7 @@ You may pass a single string to the constructor, in which case the first line be
     as a body""")
 ```
 
-Note that the default documentatino format is `rst`. You can switch to markdown by passing `format="markdown"` to the constructor, however support is not very good.
+Note that the default documentation format is `rst`. You can switch to markdown by passing `format="markdown"` to the constructor, however support is not very good.
 
 ### External Documentation