av1_encoder.dox: fix doxygen 1.9.8 warnings

fixes:
doc/dev_guide/av1_encoder.dox:590: warning: unable to resolve reference
  to 'av1_calc_iframe_target_size_one_pass_vbr()' for \ref command
doc/dev_guide/av1_encoder.dox:591: warning: unable to resolve reference
  to 'av1_calc_pframe_target_size_one_pass_vbr()' for \ref command
doc/dev_guide/av1_encoder.dox:704: warning: unable to resolve reference
  to 'av1_rc_regulate_q()' for \ref command

First seen with 1.9.5. See
https://github.com/doxygen/doxygen/issues/10895.

Change-Id: I645f633b0a6d3d7372a7dbd9329c291f3a76084a
diff --git a/doc/dev_guide/av1_encoder.dox b/doc/dev_guide/av1_encoder.dox
index a40b589..13d55e4 100644
--- a/doc/dev_guide/av1_encoder.dox
+++ b/doc/dev_guide/av1_encoder.dox
@@ -587,8 +587,13 @@
 properly optimised and behaves much like 1 pass CBR in most regards, with bits
 allocated to frames by the following functions:
 
-- \ref av1_calc_iframe_target_size_one_pass_vbr()
-- \ref av1_calc_pframe_target_size_one_pass_vbr()
+- \ref av1_calc_iframe_target_size_one_pass_vbr(
+           const struct AV1_COMP *const cpi)
+       "av1_calc_iframe_target_size_one_pass_vbr()"
+- \ref av1_calc_pframe_target_size_one_pass_vbr(
+           const struct AV1_COMP *const cpi,
+           FRAME_UPDATE_TYPE frame_update_type)
+       "av1_calc_pframe_target_size_one_pass_vbr()"
 
 \subsubsection architecture_enc_2pass_vbr 2 Pass VBR Encoding
 
@@ -701,7 +706,10 @@
 
 - \ref rc_pick_q_and_bounds()
     - \ref get_q()
-        - \ref av1_rc_regulate_q()
+        - \ref av1_rc_regulate_q(
+                   const struct AV1_COMP *cpi, int target_bits_per_frame,
+                   int active_best_quality, int active_worst_quality,
+                   int width, int height) "av1_rc_regulate_q()"
         - \ref get_rate_correction_factor()
         - \ref set_rate_correction_factor()
         - \ref find_closest_qindex_by_rate()