Add legacy fragment ids to avoid broken links

Author: gosko

documentreview/index.md

@@ -63,6 +63,7 @@ dependencies.
 
 The reviews provided by the [horizontal groups](../process/horizontal-groups.md), a subset of a full wide review, do receive special attention and much of the rest of this document focuses on how and when to conduct horizontal reviews.
 
+<span id="how_to_get_horizontal_review"><!-- legacy fragment id --></span>
 ## How to get horizontal review
 When you have published a First Public Working Draft, you should work through available "self-review" materials and request review of your results in at least the following areas.
 

meetings/tpac.md

@@ -7,6 +7,7 @@ The goal of group meetings during a W3C TPAC (Technical Plenary & Advisory Commi
 
 While W3C groups meet throughout the year in a variety of ways (teleconference, F2F), the annual TPAC plays a unique and special role in the annual calendar of a group. What sets these meetings apart is that by having the group adjacent to many other groups, the group can achieve much that it cannot without such proximity.
 
+<span id="tpac2021"><!-- legacy fragment id --></span>
 ## TPAC generic advice {#advice}
 
 1. Your meeting will be added to the [W3C Calendar of the group](https://www.w3.org/blog/2021/group-calendaring-service-enters-beta-test/) as part of the main TPAC event. Make sure you add the agenda and any other relevant materials to the entry!