fix: update RFC links and README (#3675) (#3839)

Description
---
Update in light of #3675.
For reason unknown to me, the link to RFC_template.md also has to appear in
SUMMARY.md. Otherwise, it will be a 404 as reported (somehow the HTML file is
not generated).

Motivation and Context
---
See above.

How Has This Been Tested?
---
Manual check.

RFC/README.md

@@ -2,4 +2,12 @@
 
 RFC documents for the Tari protocol
 
-The rendered version of these docs can be found at https://rfc.tari.com
+These documents are in the form of an mdbook. The rendered version of these docs can be found at https://rfc.tari.com
+
+## View local rendered version
+
+- run `cargo install mdbook`
+
+- in the `/RFC` folder run `mdbook serve`
+
+- in a browser navigate to [`localhost:3000`](http://localhost:3000)

RFC/src/SUMMARY.md

@@ -48,4 +48,5 @@
 
   - [RFC-0130: Mining](RFC-0130_Mining.md)
 
+- [RFC template](RFC_template.md)
 - [Glossary](Glossary.md)

RFC/src/about.md

@@ -9,10 +9,10 @@ iterations before reaching this point:
   not cast in stone. RFCs can, and should, undergo further evaluation and discussion by the community. RFC comments are
   best made using Github [issue]s.
 
-New RFC's should follow the format given in the [RFC template](./RFC_template.md).
+New RFC's should follow the format given in the [RFC template](RFC_template.md).
 ## Lifecycle
 
-RFCs go through the following lifecycle, which roughly corresponds to the [COSS](https://rfc.unprotocols.org/spec:2/COSS/):
+RFCs go through the following lifecycle, which roughly corresponds to the [COSS](https://github.com/unprotocols/rfc/blob/master/2/README.md):
 
 | Status      |                                                   | Description                                                                                                                                                                                                         |
 |:------------|:--------------------------------------------------|:--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|