[Docs] Replace recommonmark with MyST parser

We used recommonmark so that we can use markdown in sphinx but it is
buggy and now so switch to better supported MyST-parser.

* Fixed incorrect heading warnings in markdown.
* Added sphinx toctree to markdown using directive as required by MyST.
* Upgraded Sphinx to 4.3

Ref: https://myst-parser.readthedocs.io

1 files changed, 10 insertions, 2 deletions

diff --git a/docs/source/devguide/how-to/index.md b/docs/source/devguide/how-to/index.md
index 93a43fce1..e63c7713b 100644
--- a/docs/source/devguide/how-to/index.md
+++ b/docs/source/devguide/how-to/index.md
@@ -4,7 +4,11 @@ A collection of guides for specific issues or to cover more detail than the tuto
 
 ## Web JSON-RPC
 
-- [Connect to JSON-RPC using curl](curl-jsonrpc.md)
+```{toctree}
+:titlesonly:
+
+Connect to JSON-RPC using curl <curl-jsonrpc>
+```
 
 ## Plugins
 
@@ -12,4 +16,8 @@ A collection of guides for specific issues or to cover more detail than the tuto
 - [Create a plugin](create-plugin.md)
 -->
 
-- [Update 1.3 plugin for 2.0](update-1.3-plugin.md)
+```{toctree}
+:titlesonly:
+
+Update 1.3 plugin for 2.0 <update-1.3-plugin>
+```