Update to Material icon support in docs

Author: Vyrastas

doc/STYLE_GUIDE.md

@@ -185,17 +185,20 @@ understanding of Weave by highlighting common elements and are not official Weav
 icons.
 
 > You are not required to use these icons, but we may ask to insert them during the review
-process, in order to tie content together across the documentation site.
+process, in order to visually tie concepts together across the documentation site.
 
 Example: https://openweave.io/guides/tools#weave-heartbeat
 
 To use these icons in your content, so that they render on the openweave.io documentation site,
-surround one of the supported keywords with semicolons. The word can be upper or lowercase.
+surround one of the supported keywords with an underscore+asterisk combo.
 
 For example:
 
-*   ;Echo;
-*   ;heartbeat;
+<div>_*Echo*_</div>
+<div>_*heartbeat*_</div>
+
+The keyword can be upper or lowercase. Use of this format with unsupported keywords merely
+renders the text in italics.
 
 See the **OpenWeave Tools** page for an example of this:
 

doc/guides/tools/index.md

@@ -15,9 +15,9 @@ Tool | Description | [Standalone build](https://openweave.io/guides/build#standa
 `weave` | Generate and manage Weave certificates | `/src/tools/weave`
 `weave-device-descriptor` | Encode and decode Weave device descriptor strings for pairing QR codes | `/src/test-apps`
 [`weave-device-mgr`](/guides/tools/device-manager) | Manage the device pairing process | `/src/device-manager/python`
-`weave-heartbeat` | Send and receive <a href="https://openweave.io/guides/weave-primer/profiles#heartbeat">;Heartbeat;</a> profile messages | `/src/test-apps`
+`weave-heartbeat` | Send and receive <a href="https://openweave.io/guides/weave-primer/profiles#heartbeat">_*Heartbeat*_</a> profile messages | `/src/test-apps`
 `weave-key-export` | Send key export requests | `/src/test-apps`
-`weave-ping`| Send and receive <a href="https://openweave.io/guides/weave-primer/profiles#echo">;Echo;</a> profile messages | `/src/test-apps`
+`weave-ping`| Send and receive <a href="https://openweave.io/guides/weave-primer/profiles#echo">_*Echo*_</a> profile messages | `/src/test-apps`
 
 To build the target:
 
@@ -167,7 +167,7 @@ Primary WiFi MAC: 5C:F3:70:80:0E:77
 ## weave-heartbeat
 
 Use `weave-heartbeat` to send and receive
-<a href="https://openweave.io/guides/weave-primer/profiles#heartbeat">;Heartbeat;</a> profile messages between
+<a href="https://openweave.io/guides/weave-primer/profiles#heartbeat">_*Heartbeat*_</a> profile messages between
 two Weave nodes. Heartbeat provides a means to indicate liveness of one node to
 the other nodes in the network, or to check if a node remains connected to the
 fabric.
@@ -260,7 +260,7 @@ $ ./mock-device -a fd00:0:1:1::1
 ## weave-ping
 
 Use `weave-ping` to send and receive
-<a href="https://openweave.io/guides/weave-primer/profiles#echo">;Echo;</a> profile messages
+<a href="https://openweave.io/guides/weave-primer/profiles#echo">_*Echo*_</a> profile messages
 between two Weave nodes. An Echo payload consists of arbitrary data supplied by
 the requesting node and is expected to be echoed back verbatim in the response.
 Echo provides a means to test network connectivity and latency.