[skip-changelog] Some documentation improvement for pluggable discovery/montior (#1636)

* Fixed wrong "event" fields in pluggable monitor specs

* Better specify discoveryDependencies and monitorDependencies fields in package_index.json

Author: cmaglie

docs/package_index_json-specification.md

@@ -246,14 +246,16 @@ Each PLATFORM describes a core for a specific architecture. The fields needed ar
 - `toolsDependencies`: the tools needed by this platform. They will be installed by Boards Manager along with the
   platform. Each tool is referenced by the triple (`packager`, `name`, `version`) as previously said. Note that you can
   reference tools available in other packages as well, even if no platform of that package is installed.
-- `discoveryDependencies`: the Pluggable Discoveries needed by this platform. Each discovery is referenced by the pair
-  (`packager`, `name`), the `version` is not specified because the latest installed discovery tool will always be used.
-  Like `toolsDependencies` they will be installed by Boards Manager along with the platform and can reference tools
-  available in other packages as well, even if no platform of that package is installed.
-- `monitorDependencies`: the Pluggable Monitors needed by this platform. Each monitor is referenced by the pair
-  (`packager`, `name`), the `version` is not specified because the latest installed monitor tool will always be used.
-  Like `toolsDependencies` they will be installed by Boards Manager along with the platform and can reference tools
-  available in other packages as well, even if no platform of that package is installed.
+- `discoveryDependencies`: the Pluggable Discoveries needed by this platform. These are [tools](#tools-definitions),
+  defined exactly like the ones referenced in `toolsDependencies`. Unlike `toolsDependencies`, discoveries are
+  referenced by the pair (`packager`, `name`). The `version` is not specified because the latest installed discovery
+  tool will always be used. Like `toolsDependencies` they will be installed by Boards Manager along with the platform
+  and can reference tools available in other packages as well, even if no platform of that package is installed.
+- `monitorDependencies`: the Pluggable Monitors needed by this platform. These are [tools](#tools-definitions), defined
+  exactly like the ones referenced in `toolsDependencies`. Unlike `toolsDependencies`, monitors are referenced by the
+  pair (`packager`, `name`). The `version` is not specified because the latest installed monitor tool will always be
+  used. Like `toolsDependencies` they will be installed by Boards Manager along with the platform and can reference
+  tools available in other packages as well, even if no platform of that package is installed.
 
 The `version` field is validated by both Arduino IDE and [JSemVer](https://github.com/zafarkhaja/jsemver). Here are the
 rules Arduino IDE follows for parsing versions

docs/pluggable-monitor-specification.md

@@ -62,7 +62,7 @@ port configuration, and which parameters are available to the user.
 
 ```JSON
 {
-  "event": "describe",
+  "eventType": "describe",
   "message": "ok",
   "port_description": {
     "protocol": "serial",
@@ -127,7 +127,7 @@ The response to the command is:
 
 ```JSON
 {
-  "event": "configure",
+  "eventType": "configure",
   "message": "ok"
 }
 ```
@@ -136,7 +136,7 @@ or if there is an error:
 
 ```JSON
 {
-  "event": "configure",
+  "eventType": "configure",
   "error": true,
   "message": "invalid value for parameter baudrate: 123456"
 }
@@ -167,7 +167,7 @@ The answer to the `OPEN` command is:
 
 ```JSON
 {
-  "event": "open",
+  "eventType": "open",
   "message": "ok"
 }
 ```
@@ -177,7 +177,7 @@ other error condition happens:
 
 ```JSON
 {
-  "event": "open",
+  "eventType": "open",
   "error": true,
   "message": "unknown port /dev/ttyACM23"
 }
@@ -191,7 +191,7 @@ tool:
 
 ```JSON
 {
-  "event": "port_closed",
+  "eventType": "port_closed",
   "message": "serial port disappeared!"
 }
 ```
@@ -200,7 +200,7 @@ or
 
 ```JSON
 {
-  "event": "port_closed",
+  "eventType": "port_closed",
   "message": "lost TCP/IP connection with the client!"
 }
 ```
@@ -212,7 +212,7 @@ Client/IDE. The answer to the command is:
 
 ```JSON
 {
-  "event": "close",
+  "eventType": "close",
   "message": "ok"
 }
 ```
@@ -221,7 +221,7 @@ or in case of error
 
 ```JSON
 {
-  "event": "close",
+  "eventType": "close",
   "error": true,
   "message": "port already closed"
 }