Update get_involved.md (#41)

- Added Extension section
- Links need to be updated

docs/community/get_involved.md

@@ -27,35 +27,39 @@ To formalize this process, we've established the GTFS Governance framework, whic
 
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-## Active projects
+## Extensions
 
-The community is constantly developing new additions to the specification that could require discussions and working group meetings to accomplish their larger goals in an open source setting. Working group meetings are consensus building discussions led by a facilitator, and attended by developpers, and interested contributors.   
+Extensions are proposals to change the specification that are composed by a collection of related files and fields. Additional files and fields can be extended onto GTFS datasets to accommodate a variety of application-specific needs communicated between transit agencies and software vendors, even if these fields are not in the official specification. Once adopted, extensions are merged and documented into the official specification as a set of features. 
 
 <div class="grid cards" markdown>
 
--   :fontawesome-solid-money-check-dollar:{ .lg .middle } __GTFS-Fares v2__
-
+-   :material-bus:{ .lg .middle } __GTFS Schedule Extensions__ 
+   
     ---
 
-    GTFS-Fares v2 aims to enhance fare representation in GTFS, introducing features like fare products and rider categories.
-
-    [:octicons-arrow-right-24: Learn more](../active_projects/fares-v2)
+    [:octicons-arrow-right-24: Learn more](#)
 
--   :material-bus-sign:{ .lg .middle } __GTFS-Flex__
+-   :material-bus-marker:{ .lg .middle } __GTFS Realtime Extensions__
 
     ---
 
-    GTFS-Flex is a project to improve discoverability of Demand Responsive Transportation Services.
+    [:octicons-arrow-right-24: Learn more](#)
 
-    [:octicons-arrow-right-24: Learn more](../active_projects/flex)
+</div>
 
--   :material-bus-alert:{ .lg .middle } __GTFS Trip-Modifications__
+## Active projects
+
+The community is constantly developing new additions to the specification that could require discussions and working group meetings to accomplish their larger goals in an open source setting. Working group meetings are consensus building discussions led by a facilitator, and attended by developpers, and interested contributors.   
+
+<div class="grid cards" markdown>
+
+-   :fontawesome-solid-money-check-dollar:{ .lg .middle } __GTFS-Fares v2__
 
     ---
 
-    Trip-Modifications modify trip shapes, remove stops, and add temporary stops, useful in detour cases.
+    GTFS-Fares v2 aims to enhance fare representation in GTFS, introducing features like fare products and rider categories.
 
-    [:octicons-arrow-right-24: Learn more](#)
+    [:octicons-arrow-right-24: Learn more](../active_projects/fares-v2)
 
 -   :material-file-document-edit:{ .lg .middle } __GTFS Governance__
 
@@ -68,6 +72,7 @@ The community is constantly developing new additions to the specification that c
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+
 ## Community Resources
 
 Make sure to check out the Resources section for an extensive selection of tips, tools, and tricks. 
@@ -76,6 +81,8 @@ Make sure to check out the Resources section for an extensive selection of tips,
 
 -   :material-file-document-multiple:{ .lg .middle } __Resources__
 
+    ---
+
     [:octicons-arrow-right-24: Learn more](../../resource_library/overview/)
 
 </div>