devrpc: remove lncli API docs tag [skip ci]

The API doc generator failed after merging #6149 because of the `lncli
importgraph` tag in the proto file.
We could also fix the API doc generator by adding the "dev" build tag,
but not including any dev only features in the API docs is probably the
preferred path.

lnrpc/devrpc/dev.swagger.json

@@ -18,7 +18,7 @@
   "paths": {
     "/v2/dev/importgraph": {
       "post": {
-        "summary": "lncli: `importgraph`\nImportGraph imports a ChannelGraph into the graph database. Should only be\nused for development.",
+        "summary": "ImportGraph imports a ChannelGraph into the graph database. Should only be\nused for development.",
         "operationId": "Dev_ImportGraph",
         "responses": {
           "200": {